37 files changed, 1992 insertions, 133 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-bdi b/Documentation/ABI/testing/sysfs-class-bdi
index 5ac1e01bbd48..5f500977b42f 100644
--- a/Documentation/ABI/testing/sysfs-class-bdi
+++ b/Documentation/ABI/testing/sysfs-class-bdi
@@ -14,6 +14,10 @@ MAJOR:MINOR
         non-block filesystems which provide their own BDI, such as NFS
         and FUSE.
 
+MAJOR:MINOR-fuseblk
+
+        Value of st_dev on fuseblk filesystems.
+
 default
 
         The default backing dev, used for non-block device backed
diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl
index 77c42f40be5d..2510763295d0 100644
--- a/Documentation/DocBook/kernel-locking.tmpl
+++ b/Documentation/DocBook/kernel-locking.tmpl
@@ -703,6 +703,31 @@
 </sect1>
 </chapter>
 
+<chapter id="trylock-functions">
+ <title>The trylock Functions</title>
+  <para>
+   There are functions that try to acquire a lock only once and immediately
+   return a value telling about success or failure to acquire the lock.
+   They can be used if you need no access to the data protected with the lock
+   when some other thread is holding the lock. You should acquire the lock
+   later if you then need access to the data protected with the lock.
+  </para>
+
+  <para>
+    <function>spin_trylock()</function> does not spin but returns non-zero if
+    it acquires the spinlock on the first try or 0 if not. This function can
+    be used in all contexts like <function>spin_lock</function>: you must have
+    disabled the contexts that might interrupt you and acquire the spin lock.
+  </para>
+
+  <para>
+    <function>mutex_trylock()</function> does not suspend your task
+    but returns non-zero if it could lock the mutex on the first try
+    or 0 if not. This function cannot be safely used in hardware or software
+    interrupt contexts despite not sleeping.
+  </para>
+</chapter>
+
   <chapter id="Examples">
    <title>Common Examples</title>
     <para>
diff --git a/Documentation/DocBook/kgdb.tmpl b/Documentation/DocBook/kgdb.tmpl
index 028a8444d95e..e8acd1f03456 100644
--- a/Documentation/DocBook/kgdb.tmpl
+++ b/Documentation/DocBook/kgdb.tmpl
@@ -84,10 +84,9 @@
     runs an instance of gdb against the vmlinux file which contains
     the symbols (not boot image such as bzImage, zImage, uImage...).
     In gdb the developer specifies the connection parameters and
-    connects to kgdb.  Depending on which kgdb I/O modules exist in
-    the kernel for a given architecture, it may be possible to debug
-    the test machine's kernel with the development machine using a
-    rs232 or ethernet connection.
+    connects to kgdb.  The type of connection a developer makes with
+    gdb depends on the availability of kgdb I/O modules compiled as
+    builtin's or kernel modules in the test machine's kernel.
     </para>
   </chapter>
   <chapter id="CompilingAKernel">
@@ -223,7 +222,7 @@
   </para>
   <para>
   IMPORTANT NOTE: Using this option with kgdb over the console
-  (kgdboc) or kgdb over ethernet (kgdboe) is not supported.
+  (kgdboc) is not supported.
   </para>
   </sect1>
   </chapter>
@@ -249,18 +248,11 @@
     (gdb) target remote /dev/ttyS0
     </programlisting>
     <para>
-    Example (kgdb to a terminal server):
+    Example (kgdb to a terminal server on tcp port 2012):
     </para>
     <programlisting>
     % gdb ./vmlinux
-    (gdb) target remote udp:192.168.2.2:6443
-    </programlisting>
-    <para>
-    Example (kgdb over ethernet):
-    </para>
-    <programlisting>
-    % gdb ./vmlinux
-    (gdb) target remote udp:192.168.2.2:6443
+    (gdb) target remote 192.168.2.2:2012
     </programlisting>
     <para>
     Once connected, you can debug a kernel the way you would debug an
diff --git a/Documentation/HOWTO b/Documentation/HOWTO
index 0291ade44c17..619e8caf30db 100644
--- a/Documentation/HOWTO
+++ b/Documentation/HOWTO
@@ -377,7 +377,7 @@ Bug Reporting
 bugzilla.kernel.org is where the Linux kernel developers track kernel
 bugs.  Users are encouraged to report all bugs that they find in this
 tool.  For details on how to use the kernel bugzilla, please see:
-        http://test.kernel.org/bugzilla/faq.html
+        http://bugzilla.kernel.org/page.cgi?id=faq.html
 
 The file REPORTING-BUGS in the main kernel source directory has a good
 template for how to report a possible kernel bug, and details what kind
diff --git a/Documentation/SubmittingPatches b/Documentation/SubmittingPatches
index 9c93a03ea33b..118ca6e9404f 100644
--- a/Documentation/SubmittingPatches
+++ b/Documentation/SubmittingPatches
@@ -327,6 +327,52 @@ Some people also put extra tags at the end.  They'll just be ignored for
 now, but you can do this to mark internal company procedures or just
 point out some special detail about the sign-off. 
 
+If you are a subsystem or branch maintainer, sometimes you need to slightly
+modify patches you receive in order to merge them, because the code is not
+exactly the same in your tree and the submitters'. If you stick strictly to
+rule (c), you should ask the submitter to rediff, but this is a totally
+counter-productive waste of time and energy. Rule (b) allows you to adjust
+the code, but then it is very impolite to change one submitter's code and
+make him endorse your bugs. To solve this problem, it is recommended that
+you add a line between the last Signed-off-by header and yours, indicating
+the nature of your changes. While there is nothing mandatory about this, it
+seems like prepending the description with your mail and/or name, all
+enclosed in square brackets, is noticeable enough to make it obvious that
+you are responsible for last-minute changes. Example :
+
+        Signed-off-by: Random J Developer <random@developer.example.org>
+        [lucky@maintainer.example.org: struct foo moved from foo.c to foo.h]
+        Signed-off-by: Lucky K Maintainer <lucky@maintainer.example.org>
+
+This practise is particularly helpful if you maintain a stable branch and
+want at the same time to credit the author, track changes, merge the fix,
+and protect the submitter from complaints. Note that under no circumstances
+can you change the author's identity (the From header), as it is the one
+which appears in the changelog.
+
+Special note to back-porters: It seems to be a common and useful practise
+to insert an indication of the origin of a patch at the top of the commit
+message (just after the subject line) to facilitate tracking. For instance,
+here's what we see in 2.6-stable :
+
+    Date:   Tue May 13 19:10:30 2008 +0000
+
+        SCSI: libiscsi regression in 2.6.25: fix nop timer handling
+
+        commit 4cf1043593db6a337f10e006c23c69e5fc93e722 upstream
+
+And here's what appears in 2.4 :
+
+    Date:   Tue May 13 22:12:27 2008 +0200
+
+        wireless, airo: waitbusy() won't delay
+
+        [backport of 2.6 commit b7acbdfbd1f277c1eb23f344f899cfa4cd0bf36a]
+
+Whatever the format, this information provides a valuable help to people
+tracking your trees, and to people trying to trouble-shoot bugs in your
+tree.
+
 
 13) When to use Acked-by: and Cc:
 
diff --git a/Documentation/accounting/taskstats-struct.txt b/Documentation/accounting/taskstats-struct.txt
index 8aa7529f8258..cd784f46bf8a 100644
--- a/Documentation/accounting/taskstats-struct.txt
+++ b/Documentation/accounting/taskstats-struct.txt
@@ -24,6 +24,8 @@ There are three different groups of fields in the struct taskstats:
 
 4) Per-task and per-thread context switch count statistics
 
+5) Time accounting for SMT machines
+
 Future extension should add fields to the end of the taskstats struct, and
 should not change the relative position of each field within the struct.
 
@@ -164,4 +166,8 @@ struct taskstats {
         __u64   nvcsw;                  /* Context voluntary switch counter */
         __u64   nivcsw;                 /* Context involuntary switch counter */
 
+5) Time accounting for SMT machines
+        __u64   ac_utimescaled;         /* utime scaled on frequency etc */
+        __u64   ac_stimescaled;         /* stime scaled on frequency etc */
+        __u64   cpu_scaled_run_real_total; /* scaled cpu_run_real_total */
 }
diff --git a/Documentation/auxdisplay/cfag12864b b/Documentation/auxdisplay/cfag12864b
index b714183d4125..eb7be393a510 100644
--- a/Documentation/auxdisplay/cfag12864b
+++ b/Documentation/auxdisplay/cfag12864b
@@ -3,7 +3,7 @@
         ===================================
 
 License:                GPLv2
-Author & Maintainer:    Miguel Ojeda Sandonis <maxextreme@gmail.com>
+Author & Maintainer:    Miguel Ojeda Sandonis
 Date:                   2006-10-27
 
 
@@ -22,7 +22,7 @@ Date:			2006-10-27
 1. DRIVER INFORMATION
 ---------------------
 
-This driver support one cfag12864b display at time.
+This driver supports a cfag12864b LCD.
 
 
 ---------------------
diff --git a/Documentation/auxdisplay/cfag12864b-example.c b/Documentation/auxdisplay/cfag12864b-example.c
index 7bfac354d4c9..2caeea5e4993 100644
--- a/Documentation/auxdisplay/cfag12864b-example.c
+++ b/Documentation/auxdisplay/cfag12864b-example.c
@@ -4,7 +4,7 @@
  * Description: cfag12864b LCD userspace example program
  *     License: GPLv2
  *
- *      Author: Copyright (C) Miguel Ojeda Sandonis <maxextreme@gmail.com>
+ *      Author: Copyright (C) Miguel Ojeda Sandonis
  *        Date: 2006-10-31
  *
  *  This program is free software; you can redistribute it and/or modify
diff --git a/Documentation/auxdisplay/ks0108 b/Documentation/auxdisplay/ks0108
index 92b03b60c613..8ddda0c8ceef 100644
--- a/Documentation/auxdisplay/ks0108
+++ b/Documentation/auxdisplay/ks0108
@@ -3,7 +3,7 @@
         ==========================================
 
 License:                GPLv2
-Author & Maintainer:    Miguel Ojeda Sandonis <maxextreme@gmail.com>
+Author & Maintainer:    Miguel Ojeda Sandonis
 Date:                   2006-10-27
 
 
@@ -21,7 +21,7 @@ Date:			2006-10-27
 1. DRIVER INFORMATION
 ---------------------
 
-This driver support the ks0108 LCD controller.
+This driver supports the ks0108 LCD controller.
 
 
 ---------------------
diff --git a/Documentation/cciss.txt b/Documentation/cciss.txt
index e65736c6b8bc..63e59b8847c5 100644
--- a/Documentation/cciss.txt
+++ b/Documentation/cciss.txt
@@ -21,6 +21,11 @@ This driver is known to work with the following cards:
         * SA E200
         * SA E200i
         * SA E500
+        * SA P212
+        * SA P410
+        * SA P410i
+        * SA P411
+        * SA P812
 
 Detecting drive failures:
 -------------------------
diff --git a/Documentation/cgroups.txt b/Documentation/cgroups.txt
index 824fc0274471..d9014aa0eb68 100644
--- a/Documentation/cgroups.txt
+++ b/Documentation/cgroups.txt
@@ -390,6 +390,10 @@ If you have several tasks to attach, you have to do it one after another:
         ...
 # /bin/echo PIDn > tasks
 
+You can attach the current shell task by echoing 0:
+
+# echo 0 > tasks
+
 3. Kernel API
 =============
 
diff --git a/Documentation/controllers/devices.txt b/Documentation/controllers/devices.txt
index 4dcea42432c2..7cc6e6a60672 100644
--- a/Documentation/controllers/devices.txt
+++ b/Documentation/controllers/devices.txt
@@ -13,7 +13,7 @@ either an integer or * for all.  Access is a composition of r
 The root device cgroup starts with rwm to 'all'.  A child device
 cgroup gets a copy of the parent.  Administrators can then remove
 devices from the whitelist or add new entries.  A child cgroup can
-never receive a device access which is denied its parent.  However
+never receive a device access which is denied by its parent.  However
 when a device access is removed from a parent it will not also be
 removed from the child(ren).
 
@@ -29,7 +29,11 @@ allows cgroup 1 to read and mknod the device usually known as
 
         echo a > /cgroups/1/devices.deny
 
-will remove the default 'a *:* mrw' entry.
+will remove the default 'a *:* rwm' entry. Doing
+
+        echo a > /cgroups/1/devices.allow
+
+will add the 'a *:* rwm' entry to the whitelist.
 
 3. Security
 
diff --git a/Documentation/cpu-freq/governors.txt b/Documentation/cpu-freq/governors.txt
index 6a9c55bd556b..dcec0564d040 100644
--- a/Documentation/cpu-freq/governors.txt
+++ b/Documentation/cpu-freq/governors.txt
@@ -129,14 +129,6 @@ to its default value of '80' it means that between the checking
 intervals the CPU needs to be on average more than 80% in use to then
 decide that the CPU frequency needs to be increased.  
 
-sampling_down_factor: this parameter controls the rate that the CPU
-makes a decision on when to decrease the frequency.  When set to its
-default value of '5' it means that at 1/5 the sampling_rate the kernel
-makes a decision to lower the frequency.  Five "lower rate" decisions
-have to be made in a row before the CPU frequency is actually lower.
-If set to '1' then the frequency decreases as quickly as it increases,
-if set to '2' it decreases at half the rate of the increase.
-
 ignore_nice_load: this parameter takes a value of '0' or '1'. When
 set to '0' (its default), all processes are counted towards the
 'cpu utilisation' value.  When set to '1', the processes that are
diff --git a/Documentation/cpusets.txt b/Documentation/cpusets.txt
index fb7b361e6eea..1f5a924d1e56 100644
--- a/Documentation/cpusets.txt
+++ b/Documentation/cpusets.txt
@@ -154,13 +154,15 @@ browsing and modifying the cpusets presently known to the kernel.  No
 new system calls are added for cpusets - all support for querying and
 modifying cpusets is via this cpuset file system.
 
-The /proc/<pid>/status file for each task has two added lines,
+The /proc/<pid>/status file for each task has four added lines,
 displaying the tasks cpus_allowed (on which CPUs it may be scheduled)
 and mems_allowed (on which Memory Nodes it may obtain memory),
-in the format seen in the following example:
+in the two formats seen in the following example:
 
   Cpus_allowed:   ffffffff,ffffffff,ffffffff,ffffffff
+  Cpus_allowed_list:      0-127
   Mems_allowed:   ffffffff,ffffffff
+  Mems_allowed_list:      0-63
 
 Each cpuset is represented by a directory in the cgroup file system
 containing (on top of the standard cgroup files) the following
@@ -199,7 +201,7 @@ using the sched_setaffinity, mbind and set_mempolicy system calls.
 The following rules apply to each cpuset:
 
  - Its CPUs and Memory Nodes must be a subset of its parents.
- - It can only be marked exclusive if its parent is.
+ - It can't be marked exclusive unless its parent is.
  - If its cpu or memory is exclusive, they may not overlap any sibling.
 
 These rules, and the natural hierarchy of cpusets, enable efficient
@@ -345,7 +347,7 @@ is modified to perform an inline check for this PF_SPREAD_PAGE task
 flag, and if set, a call to a new routine cpuset_mem_spread_node()
 returns the node to prefer for the allocation.
 
-Similarly, setting 'memory_spread_cache' turns on the flag
+Similarly, setting 'memory_spread_slab' turns on the flag
 PF_SPREAD_SLAB, and appropriately marked slab caches will allocate
 pages from the node returned by cpuset_mem_spread_node().
 
@@ -542,7 +544,10 @@ otherwise initial value -1 that indicates the cpuset has no request.
    2  : search cores in a package.
    3  : search cpus in a node [= system wide on non-NUMA system]
  ( 4  : search nodes in a chunk of node [on NUMA system] )
- ( 5~ : search system wide [on NUMA system])
+ ( 5  : search system wide [on NUMA system] )
+
+The system default is architecture dependent.  The system default
+can be changed using the relax_domain_level= boot parameter.
 
 This file is per-cpuset and affect the sched domain where the cpuset
 belongs to.  Therefore if the flag 'sched_load_balance' of a cpuset
@@ -709,7 +714,10 @@ Now you want to do something with this cpuset.
 
 In this directory you can find several files:
 # ls
-cpus  cpu_exclusive  mems  mem_exclusive mem_hardwall  tasks
+cpu_exclusive  memory_migrate      mems                      tasks
+cpus           memory_pressure     notify_on_release
+mem_exclusive  memory_spread_page  sched_load_balance
+mem_hardwall   memory_spread_slab  sched_relax_domain_level
 
 Reading them will give you information about the state of this cpuset:
 the CPUs and Memory Nodes it can use, the processes that are using
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 5b3f31faed56..46ece3fba6f9 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -312,3 +312,12 @@ When:	2.6.26
 Why:    Implementation became generic; users should now include
         linux/semaphore.h instead.
 Who:    Matthew Wilcox <willy@linux.intel.com>
+
+---------------------------
+
+What:   CONFIG_THERMAL_HWMON
+When:   January 2009
+Why:    This option was introduced just to allow older lm-sensors userspace
+        to keep working over the upgrade to 2.6.26. At the scheduled time of
+        removal fixed lm-sensors (2.x or 3.x) should be readily available.
+Who:    Rene Herman <rene.herman@gmail.com>
diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 560f88dc7090..0c5086db8352 100644
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -139,8 +139,16 @@ commit=nrsec	(*)	Ext4 can be told to sync all its data and metadata
                         Setting it to very large values will improve
                         performance.
 
-barrier=1               This enables/disables barriers.  barrier=0 disables
-                        it, barrier=1 enables it.
+barrier=<0|1(*)>        This enables/disables the use of write barriers in
+                        the jbd code.  barrier=0 disables, barrier=1 enables.
+                        This also requires an IO stack which can support
+                        barriers, and if jbd gets an error on a barrier
+                        write, it will disable again with a warning.
+                        Write barriers enforce proper on-disk ordering
+                        of journal commits, making volatile disk write caches
+                        safe to use, at some performance penalty.  If
+                        your disks are battery-backed in one way or another,
+                        disabling barriers may safely improve performance.
 
 orlov           (*)     This enables the new Orlov block allocator. It is
                         enabled by default.
diff --git a/Documentation/filesystems/sysfs-pci.txt b/Documentation/filesystems/sysfs-pci.txt
index 5daa2aaec2c5..68ef48839c04 100644
--- a/Documentation/filesystems/sysfs-pci.txt
+++ b/Documentation/filesystems/sysfs-pci.txt
@@ -36,6 +36,7 @@ files, each with their own function.
        local_cpus          nearby CPU mask (cpumask, ro)
        resource            PCI resource host addresses (ascii, ro)
        resource0..N        PCI resource N, if present (binary, mmap)
+       resource0_wc..N_wc  PCI WC map resource N, if prefetchable (binary, mmap)
        rom                 PCI ROM resource, if present (binary, ro)
        subsystem_device    PCI subsystem device (ascii, ro)
        subsystem_vendor    PCI subsystem vendor (ascii, ro)
diff --git a/Documentation/ftrace.txt b/Documentation/ftrace.txt
new file mode 100644
index 000000000000..13e4bf054c38
--- /dev/null
+++ b/Documentation/ftrace.txt
@@ -0,0 +1,1353 @@
+                ftrace - Function Tracer
+                ========================
+
+Copyright 2008 Red Hat Inc.
+Author: Steven Rostedt <srostedt@redhat.com>
+
+
+Introduction
+------------
+
+Ftrace is an internal tracer designed to help out developers and
+designers of systems to find what is going on inside the kernel.
+It can be used for debugging or analyzing latencies and performance
+issues that take place outside of user-space.
+
+Although ftrace is the function tracer, it also includes an
+infrastructure that allows for other types of tracing. Some of the
+tracers that are currently in ftrace is a tracer to trace
+context switches, the time it takes for a high priority task to
+run after it was woken up, the time interrupts are disabled, and
+more.
+
+
+The File System
+---------------
+
+Ftrace uses the debugfs file system to hold the control files as well
+as the files to display output.
+
+To mount the debugfs system:
+
+  # mkdir /debug
+  # mount -t debugfs nodev /debug
+
+
+That's it! (assuming that you have ftrace configured into your kernel)
+
+After mounting the debugfs, you can see a directory called
+"tracing".  This directory contains the control and output files
+of ftrace. Here is a list of some of the key files:
+
+
+ Note: all time values are in microseconds.
+
+  current_tracer : This is used to set or display the current tracer
+                that is configured.
+
+  available_tracers : This holds the different types of tracers that
+                has been compiled into the kernel. The tracers
+                listed here can be configured by echoing in their
+                name into current_tracer.
+
+  tracing_enabled : This sets or displays whether the current_tracer
+                is activated and tracing or not. Echo 0 into this
+                file to disable the tracer or 1 (or non-zero) to
+                enable it.
+
+  trace : This file holds the output of the trace in a human readable
+                format.
+
+  latency_trace : This file shows the same trace but the information
+                is organized more to display possible latencies
+                in the system.
+
+  trace_pipe : The output is the same as the "trace" file but this
+                file is meant to be streamed with live tracing.
+                Reads from this file will block until new data
+                is retrieved. Unlike the "trace" and "latency_trace"
+                files, this file is a consumer. This means reading
+                from this file causes sequential reads to display
+                more current data. Once data is read from this
+                file, it is consumed, and will not be read
+                again with a sequential read. The "trace" and
+                "latency_trace" files are static, and if the
+                tracer isn't adding more data, they will display
+                the same information every time they are read.
+
+  iter_ctrl : This file lets the user control the amount of data
+                that is displayed in one of the above output
+                files.
+
+  trace_max_latency : Some of the tracers record the max latency.
+                For example, the time interrupts are disabled.
+                This time is saved in this file. The max trace
+                will also be stored, and displayed by either
+                "trace" or "latency_trace".  A new max trace will
+                only be recorded if the latency is greater than
+                the value in this file. (in microseconds)
+
+  trace_entries : This sets or displays the number of trace
+                entries each CPU buffer can hold. The tracer buffers
+                are the same size for each CPU, so care must be
+                taken when modifying the trace_entries. The number
+                of actually entries will be the number given
+                times the number of possible CPUS. The buffers
+                are saved as individual pages, and the actual entries
+                will always be rounded up to entries per page.
+
+                This can only be updated when the current_tracer
+                is set to "none".
+
+                NOTE: It is planned on changing the allocated buffers
+                      from being the number of possible CPUS to
+                      the number of online CPUS.
+
+  tracing_cpumask : This is a mask that lets the user only trace
+                on specified CPUS. The format is a hex string
+                representing the CPUS.
+
+  set_ftrace_filter : When dynamic ftrace is configured in, the
+                code is dynamically modified to disable calling
+                of the function profiler (mcount). This lets
+                tracing be configured in with practically no overhead
+                in performance.  This also has a side effect of
+                enabling or disabling specific functions to be
+                traced.  Echoing in names of functions into this
+                file will limit the trace to only those files.
+
+  set_ftrace_notrace: This has the opposite effect that
+                set_ftrace_filter has. Any function that is added
+                here will not be traced. If a function exists
+                in both set_ftrace_filter and set_ftrace_notrace
+                the function will _not_ bet traced.
+
+  available_filter_functions : When a function is encountered the first
+                time by the dynamic tracer, it is recorded and
+                later the call is converted into a nop. This file
+                lists the functions that have been recorded
+                by the dynamic tracer and these functions can
+                be used to set the ftrace filter by the above
+                "set_ftrace_filter" file.
+
+
+The Tracers
+-----------
+
+Here are the list of current tracers that can be configured.
+
+  ftrace - function tracer that uses mcount to trace all functions.
+                It is possible to filter out which functions that are
+                traced when dynamic ftrace is configured in.
+
+  sched_switch - traces the context switches between tasks.
+
+  irqsoff - traces the areas that disable interrupts and saves off
+                the trace with the longest max latency.
+                See tracing_max_latency.  When a new max is recorded,
+                it replaces the old trace. It is best to view this
+                trace with the latency_trace file.
+
+  preemptoff - Similar to irqsoff but traces and records the time
+                preemption is disabled.
+
+  preemptirqsoff - Similar to irqsoff and preemptoff, but traces and
+                 records the largest time irqs and/or preemption is
+                 disabled.
+
+  wakeup - Traces and records the max latency that it takes for
+                the highest priority task to get scheduled after
+                it has been woken up.
+
+  none - This is not a tracer. To remove all tracers from tracing
+                simply echo "none" into current_tracer.
+
+
+Examples of using the tracer
+----------------------------
+
+Here are typical examples of using the tracers with only controlling
+them with the debugfs interface (without using any user-land utilities).
+
+Output format:
+--------------
+
+Here's an example of the output format of the file "trace"
+
+                             --------
+# tracer: ftrace
+#
+#           TASK-PID   CPU#    TIMESTAMP  FUNCTION
+#              | |      |          |         |
+            bash-4251  [01] 10152.583854: path_put <-path_walk
+            bash-4251  [01] 10152.583855: dput <-path_put
+            bash-4251  [01] 10152.583855: _atomic_dec_and_lock <-dput
+                             --------
+
+A header is printed with the trace that is represented. In this case
+the tracer is "ftrace". Then a header showing the format. Task name
+"bash", the task PID "4251", the CPU that it was running on
+"01", the timestamp in <secs>.<usecs> format, the function name that was
+traced "path_put" and the parent function that called this function
+"path_walk".
+
+The sched_switch tracer also includes tracing of task wake ups and
+context switches.
+
+     ksoftirqd/1-7     [01]  1453.070013:      7:115:R   +  2916:115:S
+     ksoftirqd/1-7     [01]  1453.070013:      7:115:R   +    10:115:S
+     ksoftirqd/1-7     [01]  1453.070013:      7:115:R ==>    10:115:R
+        events/1-10    [01]  1453.070013:     10:115:S ==>  2916:115:R
+     kondemand/1-2916  [01]  1453.070013:   2916:115:S ==>     7:115:R
+     ksoftirqd/1-7     [01]  1453.070013:      7:115:S ==>     0:140:R
+
+Wake ups are represented by a "+" and the context switches show
+"==>".  The format is:
+
+ Context switches:
+
+       Previous task              Next Task
+
+  <pid>:<prio>:<state>  ==>  <pid>:<prio>:<state>
+
+ Wake ups:
+
+       Current task               Task waking up
+
+  <pid>:<prio>:<state>    +  <pid>:<prio>:<state>
+
+The prio is the internal kernel priority, which is inverse to the
+priority that is usually displayed by user-space tools. Zero represents
+the highest priority (99). Prio 100 starts the "nice" priorities with
+100 being equal to nice -20 and 139 being nice 19. The prio "140" is
+reserved for the idle task which is the lowest priority thread (pid 0).
+
+
+Latency trace format
+--------------------
+
+For traces that display latency times, the latency_trace file gives
+a bit more information to see why a latency happened. Here's a typical
+trace.
+
+# tracer: irqsoff
+#
+irqsoff latency trace v1.1.5 on 2.6.26-rc8
+--------------------------------------------------------------------
+ latency: 97 us, #3/3, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
+    -----------------
+    | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0)
+    -----------------
+ => started at: apic_timer_interrupt
+ => ended at:   do_softirq
+
+#                _------=> CPU#
+#               / _-----=> irqs-off
+#              | / _----=> need-resched
+#              || / _---=> hardirq/softirq
+#              ||| / _--=> preempt-depth
+#              |||| /
+#              |||||     delay
+#  cmd     pid ||||| time  |   caller
+#     \   /    |||||   \   |   /
+  <idle>-0     0d..1    0us+: trace_hardirqs_off_thunk (apic_timer_interrupt)
+  <idle>-0     0d.s.   97us : __do_softirq (do_softirq)
+  <idle>-0     0d.s1   98us : trace_hardirqs_on (do_softirq)
+
+
+vim:ft=help
+
+
+This shows that the current tracer is "irqsoff" tracing the time
+interrupts are disabled. It gives the trace version and the kernel
+this was executed on (2.6.26-rc8). Then it displays the max latency
+in microsecs (97 us). The number of trace entries displayed
+by the total number recorded (both are three: #3/3). The type of
+preemption that was used (PREEMPT). VP, KP, SP, and HP are always zero
+and reserved for later use. #P is the number of online CPUS (#P:2).
+
+The task is the process that was running when the latency happened.
+(swapper pid: 0).
+
+The start and stop that caused the latencies:
+
+  apic_timer_interrupt is where the interrupts were disabled.
+  do_softirq is where they were enabled again.
+
+The next lines after the header are the trace itself. The header
+explains which is which.
+
+  cmd: The name of the process in the trace.
+
+  pid: The PID of that process.
+
+  CPU#: The CPU that the process was running on.
+
+  irqs-off: 'd' interrupts are disabled. '.' otherwise.
+
+  need-resched: 'N' task need_resched is set, '.' otherwise.
+
+  hardirq/softirq:
+        'H' - hard irq happened inside a softirq.
+        'h' - hard irq is running
+        's' - soft irq is running
+        '.' - normal context.
+
+  preempt-depth: The level of preempt_disabled
+
+The above is mostly meaningful for kernel developers.
+
+  time: This differs from the trace output where as the trace output
+        contained a absolute timestamp. This timestamp is relative
+        to the start of the first entry in the the trace.
+
+  delay: This is just to help catch your eye a bit better. And
+        needs to be fixed to be only relative to the same CPU.
+        The marks is determined by the difference between this
+        current trace and the next trace.
+         '!' - greater than preempt_mark_thresh (default 100)
+         '+' - greater than 1 microsecond
+         ' ' - less than or equal to 1 microsecond.
+
+  The rest is the same as the 'trace' file.
+
+
+iter_ctrl
+---------
+
+The iter_ctrl file is used to control what gets printed in the trace
+output. To see what is available, simply cat the file:
+
+  cat /debug/tracing/iter_ctrl
+  print-parent nosym-offset nosym-addr noverbose noraw nohex nobin \
+ noblock nostacktrace nosched-tree
+
+To disable one of the options, echo in the option appended with "no".
+
+  echo noprint-parent > /debug/tracing/iter_ctrl
+
+To enable an option, leave off the "no".
+
+  echo sym-offest > /debug/tracing/iter_ctrl
+
+Here are the available options:
+
+  print-parent - On function traces, display the calling function
+                as well as the function being traced.
+
+  print-parent:
+   bash-4000  [01]  1477.606694: simple_strtoul <-strict_strtoul
+
+  noprint-parent:
+   bash-4000  [01]  1477.606694: simple_strtoul
+
+
+  sym-offset - Display not only the function name, but also the offset
+                in the function. For example, instead of seeing just
+                "ktime_get" you will see "ktime_get+0xb/0x20"
+
+  sym-offset:
+   bash-4000  [01]  1477.606694: simple_strtoul+0x6/0xa0
+
+  sym-addr - this will also display the function address as well as
+                the function name.
+
+  sym-addr:
+   bash-4000  [01]  1477.606694: simple_strtoul <c0339346>
+
+  verbose - This deals with the latency_trace file.
+
+    bash  4000 1 0 00000000 00010a95 [58127d26] 1720.415ms \
+    (+0.000ms): simple_strtoul (strict_strtoul)
+
+  raw - This will display raw numbers. This option is best for use with
+        user applications that can translate the raw numbers better than
+        having it done in the kernel.
+
+  hex - similar to raw, but the numbers will be in a hexadecimal format.
+
+  bin - This will print out the formats in raw binary.
+
+  block - TBD (needs update)
+
+  stacktrace - This is one of the options that changes the trace itself.
+                When a trace is recorded, so is the stack of functions.
+                This allows for back traces of trace sites.
+
+  sched-tree - TBD (any users??)
+
+
+sched_switch
+------------
+
+This tracer simply records schedule switches. Here's an example
+on how to implement it.
+
+ # echo sched_switch > /debug/tracing/current_tracer
+ # echo 1 > /debug/tracing/tracing_enabled
+ # sleep 1
+ # echo 0 > /debug/tracing/tracing_enabled
+ # cat /debug/tracing/trace
+
+# tracer: sched_switch
+#
+#           TASK-PID   CPU#    TIMESTAMP  FUNCTION
+#              | |      |          |         |
+            bash-3997  [01]   240.132281:   3997:120:R   +  4055:120:R
+            bash-3997  [01]   240.132284:   3997:120:R ==>  4055:120:R
+           sleep-4055  [01]   240.132371:   4055:120:S ==>  3997:120:R
+            bash-3997  [01]   240.132454:   3997:120:R   +  4055:120:S
+            bash-3997  [01]   240.132457:   3997:120:R ==>  4055:120:R
+           sleep-4055  [01]   240.132460:   4055:120:D ==>  3997:120:R
+            bash-3997  [01]   240.132463:   3997:120:R   +  4055:120:D
+            bash-3997  [01]   240.132465:   3997:120:R ==>  4055:120:R
+          <idle>-0     [00]   240.132589:      0:140:R   +     4:115:S
+          <idle>-0     [00]   240.132591:      0:140:R ==>     4:115:R
+     ksoftirqd/0-4     [00]   240.132595:      4:115:S ==>     0:140:R
+          <idle>-0     [00]   240.132598:      0:140:R   +     4:115:S
+          <idle>-0     [00]   240.132599:      0:140:R ==>     4:115:R
+     ksoftirqd/0-4     [00]   240.132603:      4:115:S ==>     0:140:R
+           sleep-4055  [01]   240.133058:   4055:120:S ==>  3997:120:R
+ [...]
+
+
+As we have discussed previously about this format, the header shows
+the name of the trace and points to the options. The "FUNCTION"
+is a misnomer since here it represents the wake ups and context
+switches.
+
+The sched_switch only lists the wake ups (represented with '+')
+and context switches ('==>') with the previous task or current
+first followed by the next task or task waking up. The format for both
+of these is PID:KERNEL-PRIO:TASK-STATE. Remember that the KERNEL-PRIO
+is the inverse of the actual priority with zero (0) being the highest
+priority and the nice values starting at 100 (nice -20). Below is
+a quick chart to map the kernel priority to user land priorities.
+
+  Kernel priority: 0 to 99    ==> user RT priority 99 to 0
+  Kernel priority: 100 to 139 ==> user nice -20 to 19
+  Kernel priority: 140        ==> idle task priority
+
+The task states are:
+
+ R - running : wants to run, may not actually be running
+ S - sleep   : process is waiting to be woken up (handles signals)
+ D - deep sleep : process must be woken up (ignores signals)
+ T - stopped : process suspended
+ t - traced  : process is being traced (with something like gdb)
+ Z - zombie  : process waiting to be cleaned up
+ X - unknown
+
+
+ftrace_enabled
+--------------
+
+The following tracers give different output depending on whether
+or not the sysctl ftrace_enabled is set. To set ftrace_enabled,
+one can either use the sysctl function or set it via the proc
+file system interface.
+
+  sysctl kernel.ftrace_enabled=1
+
+ or
+
+  echo 1 > /proc/sys/kernel/ftrace_enabled
+
+To disable ftrace_enabled simply replace the '1' with '0' in
+the above commands.
+
+When ftrace_enabled is set the tracers will also record the functions
+that are within the trace. The descriptions of the tracers
+will also show an example with ftrace enabled.
+
+
+irqsoff
+-------
+
+When interrupts are disabled, the CPU can not react to any other
+external event (besides NMIs and SMIs). This prevents the timer
+interrupt from triggering or the mouse interrupt from letting the
+kernel know of a new mouse event. The result is a latency with the
+reaction time.
+
+The irqsoff tracer tracks the time interrupts are disabled and when
+they are re-enabled. When a new maximum latency is hit, it saves off
+the trace so that it may be retrieved at a later time. Every time a
+new maximum in reached, the old saved trace is discarded and the new
+trace is saved.
+
+To reset the maximum, echo 0 into tracing_max_latency. Here's an
+example:
+
+ # echo irqsoff > /debug/tracing/current_tracer
+ # echo 0 > /debug/tracing/tracing_max_latency
+ # echo 1 > /debug/tracing/tracing_enabled
+ # ls -ltr
+ [...]
+ # echo 0 > /debug/tracing/tracing_enabled
+ # cat /debug/tracing/latency_trace
+# tracer: irqsoff
+#
+irqsoff latency trace v1.1.5 on 2.6.26-rc8
+--------------------------------------------------------------------
+ latency: 6 us, #3/3, CPU#1 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
+    -----------------
+    | task: bash-4269 (uid:0 nice:0 policy:0 rt_prio:0)
+    -----------------
+ => started at: copy_page_range
+ => ended at:   copy_page_range
+
+#                _------=> CPU#
+#               / _-----=> irqs-off
+#              | / _----=> need-resched
+#              || / _---=> hardirq/softirq
+#              ||| / _--=> preempt-depth
+#              |||| /
+#              |||||     delay
+#  cmd     pid ||||| time  |   caller
+#     \   /    |||||   \   |   /
+    bash-4269  1...1    0us+: _spin_lock (copy_page_range)
+    bash-4269  1...1    7us : _spin_unlock (copy_page_range)
+    bash-4269  1...2    7us : trace_preempt_on (copy_page_range)
+
+
+vim:ft=help
+
+Here we see that that we had a latency of 6 microsecs (which is
+very good). The spin_lock in copy_page_range disabled interrupts.
+The difference between the 6 and the displayed timestamp 7us is
+because the clock must have incremented between the time of recording
+the max latency and recording the function that had that latency.
+
+Note the above had ftrace_enabled not set. If we set the ftrace_enabled
+we get a much larger output:
+
+# tracer: irqsoff
+#
+irqsoff latency trace v1.1.5 on 2.6.26-rc8
+--------------------------------------------------------------------
+ latency: 50 us, #101/101, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
+    -----------------
+    | task: ls-4339 (uid:0 nice:0 policy:0 rt_prio:0)
+    -----------------
+ => started at: __alloc_pages_internal
+ => ended at:   __alloc_pages_internal
+
+#                _------=> CPU#
+#               / _-----=> irqs-off
+#              | / _----=> need-resched
+#              || / _---=> hardirq/softirq
+#              ||| / _--=> preempt-depth
+#              |||| /
+#              |||||     delay
+#  cmd     pid ||||| time  |   caller
+#     \   /    |||||   \   |   /
+      ls-4339  0...1    0us+: get_page_from_freelist (__alloc_pages_internal)
+      ls-4339  0d..1    3us : rmqueue_bulk (get_page_from_freelist)
+      ls-4339  0d..1    3us : _spin_lock (rmqueue_bulk)
+      ls-4339  0d..1    4us : add_preempt_count (_spin_lock)
+      ls-4339  0d..2    4us : __rmqueue (rmqueue_bulk)
+      ls-4339  0d..2    5us : __rmqueue_smallest (__rmqueue)
+      ls-4339  0d..2    5us : __mod_zone_page_state (__rmqueue_smallest)
+      ls-4339  0d..2    6us : __rmqueue (rmqueue_bulk)
+      ls-4339  0d..2    6us : __rmqueue_smallest (__rmqueue)
+      ls-4339  0d..2    7us : __mod_zone_page_state (__rmqueue_smallest)
+      ls-4339  0d..2    7us : __rmqueue (rmqueue_bulk)
+      ls-4339  0d..2    8us : __rmqueue_smallest (__rmqueue)
+[...]
+      ls-4339  0d..2   46us : __rmqueue_smallest (__rmqueue)
+      ls-4339  0d..2   47us : __mod_zone_page_state (__rmqueue_smallest)
+      ls-4339  0d..2   47us : __rmqueue (rmqueue_bulk)
+      ls-4339  0d..2   48us : __rmqueue_smallest (__rmqueue)
+      ls-4339  0d..2   48us : __mod_zone_page_state (__rmqueue_smallest)
+      ls-4339  0d..2   49us : _spin_unlock (rmqueue_bulk)
+      ls-4339  0d..2   49us : sub_preempt_count (_spin_unlock)
+      ls-4339  0d..1   50us : get_page_from_freelist (__alloc_pages_internal)
+      ls-4339  0d..2   51us : trace_hardirqs_on (__alloc_pages_internal)
+
+
+vim:ft=help
+
+
+Here we traced a 50 microsecond latency. But we also see all the
+functions that were called during that time. Note that enabling
+function tracing we endure an added overhead. This overhead may
+extend the latency times. But never the less, this trace has provided
+some very helpful debugging.
+
+
+preemptoff
+----------
+
+When preemption is disabled we may be able to receive interrupts but
+the task can not be preempted and a higher priority task must wait
+for preemption to be enabled again before it can preempt a lower
+priority task.
+
+The preemptoff tracer traces the places that disables preemption.
+Like the irqsoff, it records the maximum latency that preemption
+was disabled. The control of preemptoff is much like the irqsoff.
+
+ # echo preemptoff > /debug/tracing/current_tracer
+ # echo 0 > /debug/tracing/tracing_max_latency
+ # echo 1 > /debug/tracing/tracing_enabled
+ # ls -ltr
+ [...]
+ # echo 0 > /debug/tracing/tracing_enabled
+ # cat /debug/tracing/latency_trace
+# tracer: preemptoff
+#
+preemptoff latency trace v1.1.5 on 2.6.26-rc8
+--------------------------------------------------------------------
+ latency: 29 us, #3/3, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
+    -----------------
+    | task: sshd-4261 (uid:0 nice:0 policy:0 rt_prio:0)
+    -----------------
+ => started at: do_IRQ
+ => ended at:   __do_softirq
+
+#                _------=> CPU#
+#               / _-----=> irqs-off
+#              | / _----=> need-resched
+#              || / _---=> hardirq/softirq
+#              ||| / _--=> preempt-depth
+#              |||| /
+#              |||||     delay
+#  cmd     pid ||||| time  |   caller
+#     \   /    |||||   \   |   /
+    sshd-4261  0d.h.    0us+: irq_enter (do_IRQ)
+    sshd-4261  0d.s.   29us : _local_bh_enable (__do_softirq)
+    sshd-4261  0d.s1   30us : trace_preempt_on (__do_softirq)
+
+
+vim:ft=help
+
+This has some more changes. Preemption was disabled when an interrupt
+came in (notice the 'h'), and was enabled while doing a softirq.
+(notice the 's'). But we also see that interrupts have been disabled
+when entering the preempt off section and leaving it (the 'd').
+We do not know if interrupts were enabled in the mean time.
+
+# tracer: preemptoff
+#
+preemptoff latency trace v1.1.5 on 2.6.26-rc8
+--------------------------------------------------------------------
+ latency: 63 us, #87/87, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
+    -----------------
+    | task: sshd-4261 (uid:0 nice:0 policy:0 rt_prio:0)
+    -----------------
+ => started at: remove_wait_queue
+ => ended at:   __do_softirq
+
+#                _------=> CPU#
+#               / _-----=> irqs-off
+#              | / _----=> need-resched
+#              || / _---=> hardirq/softirq
+#              ||| / _--=> preempt-depth
+#              |||| /
+#              |||||     delay
+#  cmd     pid ||||| time  |   caller
+#     \   /    |||||   \   |   /
+    sshd-4261  0d..1    0us : _spin_lock_irqsave (remove_wait_queue)
+    sshd-4261  0d..1    1us : _spin_unlock_irqrestore (remove_wait_queue)
+    sshd-4261  0d..1    2us : do_IRQ (common_interrupt)
+    sshd-4261  0d..1    2us : irq_enter (do_IRQ)
+    sshd-4261  0d..1    2us : idle_cpu (irq_enter)
+    sshd-4261  0d..1    3us : add_preempt_count (irq_enter)
+    sshd-4261  0d.h1    3us : idle_cpu (irq_enter)
+    sshd-4261  0d.h.    4us : handle_fasteoi_irq (do_IRQ)
+[...]
+    sshd-4261  0d.h.   12us : add_preempt_count (_spin_lock)
+    sshd-4261  0d.h1   12us : ack_ioapic_quirk_irq (handle_fasteoi_irq)
+    sshd-4261  0d.h1   13us : move_native_irq (ack_ioapic_quirk_irq)
+    sshd-4261  0d.h1   13us : _spin_unlock (handle_fasteoi_irq)
+    sshd-4261  0d.h1   14us : sub_preempt_count (_spin_unlock)
+    sshd-4261  0d.h1   14us : irq_exit (do_IRQ)
+    sshd-4261  0d.h1   15us : sub_preempt_count (irq_exit)
+    sshd-4261  0d..2   15us : do_softirq (irq_exit)
+    sshd-4261  0d...   15us : __do_softirq (do_softirq)
+    sshd-4261  0d...   16us : __local_bh_disable (__do_softirq)
+    sshd-4261  0d...   16us+: add_preempt_count (__local_bh_disable)
+    sshd-4261  0d.s4   20us : add_preempt_count (__local_bh_disable)
+    sshd-4261  0d.s4   21us : sub_preempt_count (local_bh_enable)
+    sshd-4261  0d.s5   21us : sub_preempt_count (local_bh_enable)
+[...]
+    sshd-4261  0d.s6   41us : add_preempt_count (__local_bh_disable)
+    sshd-4261  0d.s6   42us : sub_preempt_count (local_bh_enable)
+    sshd-4261  0d.s7   42us : sub_preempt_count (local_bh_enable)
+    sshd-4261  0d.s5   43us : add_preempt_count (__local_bh_disable)
+    sshd-4261  0d.s5   43us : sub_preempt_count (local_bh_enable_ip)
+    sshd-4261  0d.s6   44us : sub_preempt_count (local_bh_enable_ip)
+    sshd-4261  0d.s5   44us : add_preempt_count (__local_bh_disable)
+    sshd-4261  0d.s5   45us : sub_preempt_count (local_bh_enable)
+[...]
+    sshd-4261  0d.s.   63us : _local_bh_enable (__do_softirq)
+    sshd-4261  0d.s1   64us : trace_preempt_on (__do_softirq)
+
+
+The above is an example of the preemptoff trace with ftrace_enabled
+set. Here we see that interrupts were disabled the entire time.
+The irq_enter code lets us know that we entered an interrupt 'h'.
+Before that, the functions being traced still show that it is not
+in an interrupt, but we can see by the functions themselves that
+this is not the case.
+
+Notice that the __do_softirq when called doesn't have a preempt_count.
+It may seem that we missed a preempt enabled. What really happened
+is that the preempt count is held on the threads stack and we
+switched to the softirq stack (4K stacks in effect). The code
+does not copy the preempt count, but because interrupts are disabled
+we don't need to worry about it. Having a tracer like this is good
+to let people know what really happens inside the kernel.
+
+
+preemptirqsoff
+--------------
+
+Knowing the locations that have interrupts disabled or preemption
+disabled for the longest times is helpful. But sometimes we would
+like to know when either preemption and/or interrupts are disabled.
+
+The following code:
+
+    local_irq_disable();
+    call_function_with_irqs_off();
+    preempt_disable();
+    call_function_with_irqs_and_preemption_off();
+    local_irq_enable();
+    call_function_with_preemption_off();
+    preempt_enable();
+
+The irqsoff tracer will record the total length of
+call_function_with_irqs_off() and
+call_function_with_irqs_and_preemption_off().
+
+The preemptoff tracer will record the total length of
+call_function_with_irqs_and_preemption_off() and
+call_function_with_preemption_off().
+
+But neither will trace the time that interrupts and/or preemption
+is disabled. This total time is the time that we can not schedule.
+To record this time, use the preemptirqsoff tracer.
+
+Again, using this trace is much like the irqsoff and preemptoff tracers.
+
+ # echo preemptoff > /debug/tracing/current_tracer
+ # echo 0 > /debug/tracing/tracing_max_latency
+ # echo 1 > /debug/tracing/tracing_enabled
+ # ls -ltr
+ [...]
+ # echo 0 > /debug/tracing/tracing_enabled
+ # cat /debug/tracing/latency_trace
+# tracer: preemptirqsoff
+#
+preemptirqsoff latency trace v1.1.5 on 2.6.26-rc8
+--------------------------------------------------------------------
+ latency: 293 us, #3/3, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
+    -----------------
+    | task: ls-4860 (uid:0 nice:0 policy:0 rt_prio:0)
+    -----------------
+ => started at: apic_timer_interrupt
+ => ended at:   __do_softirq
+
+#                _------=> CPU#
+#               / _-----=> irqs-off
+#              | / _----=> need-resched
+#              || / _---=> hardirq/softirq
+#              ||| / _--=> preempt-depth
+#              |||| /
+#              |||||     delay
+#  cmd     pid ||||| time  |   caller
+#     \   /    |||||   \   |   /
+      ls-4860  0d...    0us!: trace_hardirqs_off_thunk (apic_timer_interrupt)
+      ls-4860  0d.s.  294us : _local_bh_enable (__do_softirq)
+      ls-4860  0d.s1  294us : trace_preempt_on (__do_softirq)
+
+
+vim:ft=help
+
+
+The trace_hardirqs_off_thunk is called from assembly on x86 when
+interrupts are disabled in the assembly code. Without the function
+tracing, we don't know if interrupts were enabled within the preemption
+points. We do see that it started with preemption enabled.
+
+Here is a trace with ftrace_enabled set:
+
+
+# tracer: preemptirqsoff
+#
+preemptirqsoff latency trace v1.1.5 on 2.6.26-rc8
+--------------------------------------------------------------------
+ latency: 105 us, #183/183, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
+    -----------------
+    | task: sshd-4261 (uid:0 nice:0 policy:0 rt_prio:0)
+    -----------------
+ => started at: write_chan
+ => ended at:   __do_softirq
+
+#                _------=> CPU#
+#               / _-----=> irqs-off
+#              | / _----=> need-resched
+#              || / _---=> hardirq/softirq
+#              ||| / _--=> preempt-depth
+#              |||| /
+#              |||||     delay
+#  cmd     pid ||||| time  |   caller
+#     \   /    |||||   \   |   /
+      ls-4473  0.N..    0us : preempt_schedule (write_chan)
+      ls-4473  0dN.1    1us : _spin_lock (schedule)
+      ls-4473  0dN.1    2us : add_preempt_count (_spin_lock)
+      ls-4473  0d..2    2us : put_prev_task_fair (schedule)
+[...]
+      ls-4473  0d..2   13us : set_normalized_timespec (ktime_get_ts)
+      ls-4473  0d..2   13us : __switch_to (schedule)
+    sshd-4261  0d..2   14us : finish_task_switch (schedule)
+    sshd-4261  0d..2   14us : _spin_unlock_irq (finish_task_switch)
+    sshd-4261  0d..1   15us : add_preempt_count (_spin_lock_irqsave)
+    sshd-4261  0d..2   16us : _spin_unlock_irqrestore (hrtick_set)
+    sshd-4261  0d..2   16us : do_IRQ (common_interrupt)
+    sshd-4261  0d..2   17us : irq_enter (do_IRQ)
+    sshd-4261  0d..2   17us : idle_cpu (irq_enter)
+    sshd-4261  0d..2   18us : add_preempt_count (irq_enter)
+    sshd-4261  0d.h2   18us : idle_cpu (irq_enter)
+    sshd-4261  0d.h.   18us : handle_fasteoi_irq (do_IRQ)
+    sshd-4261  0d.h.   19us : _spin_lock (handle_fasteoi_irq)
+    sshd-4261  0d.h.   19us : add_preempt_count (_spin_lock)
+    sshd-4261  0d.h1   20us : _spin_unlock (handle_fasteoi_irq)
+    sshd-4261  0d.h1   20us : sub_preempt_count (_spin_unlock)
+[...]
+    sshd-4261  0d.h1   28us : _spin_unlock (handle_fasteoi_irq)
+    sshd-4261  0d.h1   29us : sub_preempt_count (_spin_unlock)
+    sshd-4261  0d.h2   29us : irq_exit (do_IRQ)
+    sshd-4261  0d.h2   29us : sub_preempt_count (irq_exit)
+    sshd-4261  0d..3   30us : do_softirq (irq_exit)
+    sshd-4261  0d...   30us : __do_softirq (do_softirq)
+    sshd-4261  0d...   31us : __local_bh_disable (__do_softirq)
+    sshd-4261  0d...   31us+: add_preempt_count (__local_bh_disable)
+    sshd-4261  0d.s4   34us : add_preempt_count (__local_bh_disable)
+[...]
+    sshd-4261  0d.s3   43us : sub_preempt_count (local_bh_enable_ip)
+    sshd-4261  0d.s4   44us : sub_preempt_count (local_bh_enable_ip)
+    sshd-4261  0d.s3   44us : smp_apic_timer_interrupt (apic_timer_interrupt)
+    sshd-4261  0d.s3   45us : irq_enter (smp_apic_timer_interrupt)
+    sshd-4261  0d.s3   45us : idle_cpu (irq_enter)
+    sshd-4261  0d.s3   46us : add_preempt_count (irq_enter)
+    sshd-4261  0d.H3   46us : idle_cpu (irq_enter)
+    sshd-4261  0d.H3   47us : hrtimer_interrupt (smp_apic_timer_interrupt)
+    sshd-4261  0d.H3   47us : ktime_get (hrtimer_interrupt)
+[...]
+    sshd-4261  0d.H3   81us : tick_program_event (hrtimer_interrupt)
+    sshd-4261  0d.H3   82us : ktime_get (tick_program_event)
+    sshd-4261  0d.H3   82us : ktime_get_ts (ktime_get)
+    sshd-4261  0d.H3   83us : getnstimeofday (ktime_get_ts)
+    sshd-4261  0d.H3   83us : set_normalized_timespec (ktime_get_ts)
+    sshd-4261  0d.H3   84us : clockevents_program_event (tick_program_event)
+    sshd-4261  0d.H3   84us : lapic_next_event (clockevents_program_event)
+    sshd-4261  0d.H3   85us : irq_exit (smp_apic_timer_interrupt)
+    sshd-4261  0d.H3   85us : sub_preempt_count (irq_exit)
+    sshd-4261  0d.s4   86us : sub_preempt_count (irq_exit)
+    sshd-4261  0d.s3   86us : add_preempt_count (__local_bh_disable)
+[...]
+    sshd-4261  0d.s1   98us : sub_preempt_count (net_rx_action)
+    sshd-4261  0d.s.   99us : add_preempt_count (_spin_lock_irq)
+    sshd-4261  0d.s1   99us+: _spin_unlock_irq (run_timer_softirq)
+    sshd-4261  0d.s.  104us : _local_bh_enable (__do_softirq)
+    sshd-4261  0d.s.  104us : sub_preempt_count (_local_bh_enable)
+    sshd-4261  0d.s.  105us : _local_bh_enable (__do_softirq)
+    sshd-4261  0d.s1  105us : trace_preempt_on (__do_softirq)
+
+
+This is a very interesting trace. It started with the preemption of
+the ls task. We see that the task had the "need_resched" bit set
+with the 'N' in the trace.  Interrupts are disabled in the spin_lock
+and the trace started. We see that a schedule took place to run
+sshd.  When the interrupts were enabled we took an interrupt.
+On return of the interrupt the softirq ran. We took another interrupt
+while running the softirq as we see with the capital 'H'.
+
+
+wakeup
+------
+
+In Real-Time environment it is very important to know the wakeup
+time it takes for the highest priority task that wakes up to the
+time it executes. This is also known as "schedule latency".
+I stress the point that this is about RT tasks. It is also important
+to know the scheduling latency of non-RT tasks, but the average
+schedule latency is better for non-RT tasks. Tools like
+LatencyTop is more appropriate for such measurements.
+
+Real-Time environments is interested in the worst case latency.
+That is the longest latency it takes for something to happen, and
+not the average. We can have a very fast scheduler that may only
+have a large latency once in a while, but that would not work well
+with Real-Time tasks.  The wakeup tracer was designed to record
+the worst case wakeups of RT tasks. Non-RT tasks are not recorded
+because the tracer only records one worst case and tracing non-RT
+tasks that are unpredictable will overwrite the worst case latency
+of RT tasks.
+
+Since this tracer only deals with RT tasks, we will run this slightly
+different than we did with the previous tracers. Instead of performing
+an 'ls' we will run 'sleep 1' under 'chrt' which changes the
+priority of the task.
+
+ # echo wakeup > /debug/tracing/current_tracer
+ # echo 0 > /debug/tracing/tracing_max_latency
+ # echo 1 > /debug/tracing/tracing_enabled
+ # chrt -f 5 sleep 1
+ # echo 0 > /debug/tracing/tracing_enabled
+ # cat /debug/tracing/latency_trace
+# tracer: wakeup
+#
+wakeup latency trace v1.1.5 on 2.6.26-rc8
+--------------------------------------------------------------------
+ latency: 4 us, #2/2, CPU#1 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
+    -----------------
+    | task: sleep-4901 (uid:0 nice:0 policy:1 rt_prio:5)
+    -----------------
+
+#                _------=> CPU#
+#               / _-----=> irqs-off
+#              | / _----=> need-resched
+#              || / _---=> hardirq/softirq
+#              ||| / _--=> preempt-depth
+#              |||| /
+#              |||||     delay
+#  cmd     pid ||||| time  |   caller
+#     \   /    |||||   \   |   /
+  <idle>-0     1d.h4    0us+: try_to_wake_up (wake_up_process)
+  <idle>-0     1d..4    4us : schedule (cpu_idle)
+
+
+vim:ft=help
+
+
+Running this on an idle system we see that it only took 4 microseconds
+to perform the task switch.  Note, since the trace marker in the
+schedule is before the actual "switch" we stop the tracing when
+the recorded task is about to schedule in. This may change if
+we add a new marker at the end of the scheduler.
+
+Notice that the recorded task is 'sleep' with the PID of 4901 and it
+has an rt_prio of 5. This priority is user-space priority and not
+the internal kernel priority. The policy is 1 for SCHED_FIFO and 2
+for SCHED_RR.
+
+Doing the same with chrt -r 5 and ftrace_enabled set.
+
+# tracer: wakeup
+#
+wakeup latency trace v1.1.5 on 2.6.26-rc8
+--------------------------------------------------------------------
+ latency: 50 us, #60/60, CPU#1 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
+    -----------------
+    | task: sleep-4068 (uid:0 nice:0 policy:2 rt_prio:5)
+    -----------------
+
+#                _------=> CPU#
+#               / _-----=> irqs-off
+#              | / _----=> need-resched
+#              || / _---=> hardirq/softirq
+#              ||| / _--=> preempt-depth
+#              |||| /
+#              |||||     delay
+#  cmd     pid ||||| time  |   caller
+#     \   /    |||||   \   |   /
+ksoftirq-7     1d.H3    0us : try_to_wake_up (wake_up_process)
+ksoftirq-7     1d.H4    1us : sub_preempt_count (marker_probe_cb)
+ksoftirq-7     1d.H3    2us : check_preempt_wakeup (try_to_wake_up)
+ksoftirq-7     1d.H3    3us : update_curr (check_preempt_wakeup)
+ksoftirq-7     1d.H3    4us : calc_delta_mine (update_curr)
+ksoftirq-7     1d.H3    5us : __resched_task (check_preempt_wakeup)
+ksoftirq-7     1d.H3    6us : task_wake_up_rt (try_to_wake_up)
+ksoftirq-7     1d.H3    7us : _spin_unlock_irqrestore (try_to_wake_up)
+[...]
+ksoftirq-7     1d.H2   17us : irq_exit (smp_apic_timer_interrupt)
+ksoftirq-7     1d.H2   18us : sub_preempt_count (irq_exit)
+ksoftirq-7     1d.s3   19us : sub_preempt_count (irq_exit)
+ksoftirq-7     1..s2   20us : rcu_process_callbacks (__do_softirq)
+[...]
+ksoftirq-7     1..s2   26us : __rcu_process_callbacks (rcu_process_callbacks)
+ksoftirq-7     1d.s2   27us : _local_bh_enable (__do_softirq)
+ksoftirq-7     1d.s2   28us : sub_preempt_count (_local_bh_enable)
+ksoftirq-7     1.N.3   29us : sub_preempt_count (ksoftirqd)
+ksoftirq-7     1.N.2   30us : _cond_resched (ksoftirqd)
+ksoftirq-7     1.N.2   31us : __cond_resched (_cond_resched)
+ksoftirq-7     1.N.2   32us : add_preempt_count (__cond_resched)
+ksoftirq-7     1.N.2   33us : schedule (__cond_resched)
+ksoftirq-7     1.N.2   33us : add_preempt_count (schedule)
+ksoftirq-7     1.N.3   34us : hrtick_clear (schedule)
+ksoftirq-7     1dN.3   35us : _spin_lock (schedule)
+ksoftirq-7     1dN.3   36us : add_preempt_count (_spin_lock)
+ksoftirq-7     1d..4   37us : put_prev_task_fair (schedule)
+ksoftirq-7     1d..4   38us : update_curr (put_prev_task_fair)
+[...]
+ksoftirq-7     1d..5   47us : _spin_trylock (tracing_record_cmdline)
+ksoftirq-7     1d..5   48us : add_preempt_count (_spin_trylock)
+ksoftirq-7     1d..6   49us : _spin_unlock (tracing_record_cmdline)
+ksoftirq-7     1d..6   49us : sub_preempt_count (_spin_unlock)
+ksoftirq-7     1d..4   50us : schedule (__cond_resched)
+
+The interrupt went off while running ksoftirqd. This task runs at
+SCHED_OTHER. Why didn't we see the 'N' set early? This may be
+a harmless bug with x86_32 and 4K stacks. The need_reched() function
+that tests if we need to reschedule looks on the actual stack.
+Where as the setting of the NEED_RESCHED bit happens on the
+task's stack. But because we are in a hard interrupt, the test
+is with the interrupts stack which has that to be false. We don't
+see the 'N' until we switch back to the task's stack.
+
+ftrace
+------
+
+ftrace is not only the name of the tracing infrastructure, but it
+is also a name of one of the tracers. The tracer is the function
+tracer. Enabling the function tracer can be done from the
+debug file system. Make sure the ftrace_enabled is set otherwise
+this tracer is a nop.
+
+ # sysctl kernel.ftrace_enabled=1
+ # echo ftrace > /debug/tracing/current_tracer
+ # echo 1 > /debug/tracing/tracing_enabled
+ # usleep 1
+ # echo 0 > /debug/tracing/tracing_enabled
+ # cat /debug/tracing/trace
+# tracer: ftrace
+#
+#           TASK-PID   CPU#    TIMESTAMP  FUNCTION
+#              | |      |          |         |
+            bash-4003  [00]   123.638713: finish_task_switch <-schedule
+            bash-4003  [00]   123.638714: _spin_unlock_irq <-finish_task_switch
+            bash-4003  [00]   123.638714: sub_preempt_count <-_spin_unlock_irq
+            bash-4003  [00]   123.638715: hrtick_set <-schedule
+            bash-4003  [00]   123.638715: _spin_lock_irqsave <-hrtick_set
+            bash-4003  [00]   123.638716: add_preempt_count <-_spin_lock_irqsave
+            bash-4003  [00]   123.638716: _spin_unlock_irqrestore <-hrtick_set
+            bash-4003  [00]   123.638717: sub_preempt_count <-_spin_unlock_irqrestore
+            bash-4003  [00]   123.638717: hrtick_clear <-hrtick_set
+            bash-4003  [00]   123.638718: sub_preempt_count <-schedule
+            bash-4003  [00]   123.638718: sub_preempt_count <-preempt_schedule
+            bash-4003  [00]   123.638719: wait_for_completion <-__stop_machine_run
+            bash-4003  [00]   123.638719: wait_for_common <-wait_for_completion
+            bash-4003  [00]   123.638720: _spin_lock_irq <-wait_for_common
+            bash-4003  [00]   123.638720: add_preempt_count <-_spin_lock_irq
+[...]
+
+
+Note: It is sometimes better to enable or disable tracing directly from
+a program, because the buffer may be overflowed by the echo commands
+before you get to the point you want to trace. It is also easier to
+stop the tracing at the point that you hit the part that you are
+interested in. Since the ftrace buffer is a ring buffer with the
+oldest data being overwritten, usually it is sufficient to start the
+tracer with an echo command but have you code stop it. Something
+like the following is usually appropriate for this.
+
+int trace_fd;
+[...]
+int main(int argc, char *argv[]) {
+        [...]
+        trace_fd = open("/debug/tracing/tracing_enabled", O_WRONLY);
+        [...]
+        if (condition_hit()) {
+        write(trace_fd, "0", 1);
+        }
+        [...]
+}
+
+
+dynamic ftrace
+--------------
+
+If CONFIG_DYNAMIC_FTRACE is set, then the system will run with
+virtually no overhead when function tracing is disabled. The way
+this works is the mcount function call (placed at the start of
+every kernel function, produced by the -pg switch in gcc), starts
+of pointing to a simple return.
+
+When dynamic ftrace is initialized, it calls kstop_machine to make it
+act like a uniprocessor so that it can freely modify code without
+worrying about other processors executing that same code.  At
+initialization, the mcount calls are change to call a "record_ip"
+function.  After this, the first time a kernel function is called,
+it has the calling address saved in a hash table.
+
+Later on the ftraced kernel thread is awoken and will again call
+kstop_machine if new functions have been recorded. The ftraced thread
+will change all calls to mcount to "nop".  Just calling mcount
+and having mcount return has shown a 10% overhead. By converting
+it to a nop, there is no recordable overhead to the system.
+
+One special side-effect to the recording of the functions being
+traced, is that we can now selectively choose which functions we
+want to trace and which ones we want the mcount calls to remain as
+nops.
+
+Two files that contain to the enabling and disabling of recorded
+functions are:
+
+  set_ftrace_filter
+
+and
+
+  set_ftrace_notrace
+
+A list of available functions that you can add to this files is listed
+in:
+
+   available_filter_functions
+
+ # cat /debug/tracing/available_filter_functions
+put_prev_task_idle
+kmem_cache_create
+pick_next_task_rt
+get_online_cpus
+pick_next_task_fair
+mutex_lock
+[...]
+
+If I'm only interested in sys_nanosleep and hrtimer_interrupt:
+
+ # echo sys_nanosleep hrtimer_interrupt \
+                > /debug/tracing/set_ftrace_filter
+ # echo ftrace > /debug/tracing/current_tracer
+ # echo 1 > /debug/tracing/tracing_enabled
+ # usleep 1
+ # echo 0 > /debug/tracing/tracing_enabled
+ # cat /debug/tracing/trace
+# tracer: ftrace
+#
+#           TASK-PID   CPU#    TIMESTAMP  FUNCTION
+#              | |      |          |         |
+          usleep-4134  [00]  1317.070017: hrtimer_interrupt <-smp_apic_timer_interrupt
+          usleep-4134  [00]  1317.070111: sys_nanosleep <-syscall_call
+          <idle>-0     [00]  1317.070115: hrtimer_interrupt <-smp_apic_timer_interrupt
+
+To see what functions are being traced, you can cat the file:
+
+ # cat /debug/tracing/set_ftrace_filter
+hrtimer_interrupt
+sys_nanosleep
+
+
+Perhaps this isn't enough. The filters also allow simple wild cards.
+Only the following is currently available
+
+  <match>*  - will match functions that begins with <match>
+  *<match>  - will match functions that end with <match>
+  *<match>* - will match functions that have <match> in it
+
+Thats all the wild cards that are allowed.
+
+  <match>*<match> will not work.
+
+ # echo hrtimer_* > /debug/tracing/set_ftrace_filter
+
+Produces:
+
+# tracer: ftrace
+#
+#           TASK-PID   CPU#    TIMESTAMP  FUNCTION
+#              | |      |          |         |
+            bash-4003  [00]  1480.611794: hrtimer_init <-copy_process
+            bash-4003  [00]  1480.611941: hrtimer_start <-hrtick_set
+            bash-4003  [00]  1480.611956: hrtimer_cancel <-hrtick_clear
+            bash-4003  [00]  1480.611956: hrtimer_try_to_cancel <-hrtimer_cancel
+          <idle>-0     [00]  1480.612019: hrtimer_get_next_event <-get_next_timer_interrupt
+          <idle>-0     [00]  1480.612025: hrtimer_get_next_event <-get_next_timer_interrupt
+          <idle>-0     [00]  1480.612032: hrtimer_get_next_event <-get_next_timer_interrupt
+          <idle>-0     [00]  1480.612037: hrtimer_get_next_event <-get_next_timer_interrupt
+          <idle>-0     [00]  1480.612382: hrtimer_get_next_event <-get_next_timer_interrupt
+
+
+Notice that we lost the sys_nanosleep.
+
+ # cat /debug/tracing/set_ftrace_filter
+hrtimer_run_queues
+hrtimer_run_pending
+hrtimer_init
+hrtimer_cancel
+hrtimer_try_to_cancel
+hrtimer_forward
+hrtimer_start
+hrtimer_reprogram
+hrtimer_force_reprogram
+hrtimer_get_next_event
+hrtimer_interrupt
+hrtimer_nanosleep
+hrtimer_wakeup
+hrtimer_get_remaining
+hrtimer_get_res
+hrtimer_init_sleeper
+
+
+This is because the '>' and '>>' act just like they do in bash.
+To rewrite the filters, use '>'
+To append to the filters, use '>>'
+
+To clear out a filter so that all functions will be recorded again.
+
+ # echo > /debug/tracing/set_ftrace_filter
+ # cat /debug/tracing/set_ftrace_filter
+ #
+
+Again, now we want to append.
+
+ # echo sys_nanosleep > /debug/tracing/set_ftrace_filter
+ # cat /debug/tracing/set_ftrace_filter
+sys_nanosleep
+ # echo hrtimer_* >> /debug/tracing/set_ftrace_filter
+ # cat /debug/tracing/set_ftrace_filter
+hrtimer_run_queues
+hrtimer_run_pending
+hrtimer_init
+hrtimer_cancel
+hrtimer_try_to_cancel
+hrtimer_forward
+hrtimer_start
+hrtimer_reprogram
+hrtimer_force_reprogram
+hrtimer_get_next_event
+hrtimer_interrupt
+sys_nanosleep
+hrtimer_nanosleep
+hrtimer_wakeup
+hrtimer_get_remaining
+hrtimer_get_res
+hrtimer_init_sleeper
+
+
+The set_ftrace_notrace prevents those functions from being traced.
+
+ # echo '*preempt*' '*lock*' > /debug/tracing/set_ftrace_notrace
+
+Produces:
+
+# tracer: ftrace
+#
+#           TASK-PID   CPU#    TIMESTAMP  FUNCTION
+#              | |      |          |         |
+            bash-4043  [01]   115.281644: finish_task_switch <-schedule
+            bash-4043  [01]   115.281645: hrtick_set <-schedule
+            bash-4043  [01]   115.281645: hrtick_clear <-hrtick_set
+            bash-4043  [01]   115.281646: wait_for_completion <-__stop_machine_run
+            bash-4043  [01]   115.281647: wait_for_common <-wait_for_completion
+            bash-4043  [01]   115.281647: kthread_stop <-stop_machine_run
+            bash-4043  [01]   115.281648: init_waitqueue_head <-kthread_stop
+            bash-4043  [01]   115.281648: wake_up_process <-kthread_stop
+            bash-4043  [01]   115.281649: try_to_wake_up <-wake_up_process
+
+We can see that there's no more lock or preempt tracing.
+
+ftraced
+-------
+
+As mentioned above, when dynamic ftrace is configured in, a kernel
+thread wakes up once a second and checks to see if there are mcount
+calls that need to be converted into nops. If there is not, then
+it simply goes back to sleep. But if there is, it will call
+kstop_machine to convert the calls to nops.
+
+There may be a case that you do not want this added latency.
+Perhaps you are doing some audio recording and this activity might
+cause skips in the playback. There is an interface to disable
+and enable the ftraced kernel thread.
+
+ # echo 0 > /debug/tracing/ftraced_enabled
+
+This will disable the calling of the kstop_machine to update the
+mcount calls to nops. Remember that there's a large overhead
+to calling mcount. Without this kernel thread, that overhead will
+exist.
+
+Any write to the ftraced_enabled file will cause the kstop_machine
+to run if there are recorded calls to mcount. This means that a
+user can manually perform the updates when they want to by simply
+echoing a '0' into the ftraced_enabled file.
+
+The updates are also done at the beginning of enabling a tracer
+that uses ftrace function recording.
+
+
+trace_pipe
+----------
+
+The trace_pipe outputs the same as trace, but the effect on the
+tracing is different. Every read from trace_pipe is consumed.
+This means that subsequent reads will be different. The trace
+is live.
+
+ # echo ftrace > /debug/tracing/current_tracer
+ # cat /debug/tracing/trace_pipe > /tmp/trace.out &
+[1] 4153
+ # echo 1 > /debug/tracing/tracing_enabled
+ # usleep 1
+ # echo 0 > /debug/tracing/tracing_enabled
+ # cat /debug/tracing/trace
+# tracer: ftrace
+#
+#           TASK-PID   CPU#    TIMESTAMP  FUNCTION
+#              | |      |          |         |
+
+ #
+ # cat /tmp/trace.out
+            bash-4043  [00] 41.267106: finish_task_switch <-schedule
+            bash-4043  [00] 41.267106: hrtick_set <-schedule
+            bash-4043  [00] 41.267107: hrtick_clear <-hrtick_set
+            bash-4043  [00] 41.267108: wait_for_completion <-__stop_machine_run
+            bash-4043  [00] 41.267108: wait_for_common <-wait_for_completion
+            bash-4043  [00] 41.267109: kthread_stop <-stop_machine_run
+            bash-4043  [00] 41.267109: init_waitqueue_head <-kthread_stop
+            bash-4043  [00] 41.267110: wake_up_process <-kthread_stop
+            bash-4043  [00] 41.267110: try_to_wake_up <-wake_up_process
+            bash-4043  [00] 41.267111: select_task_rq_rt <-try_to_wake_up
+
+
+Note, reading the trace_pipe will block until more input is added.
+By changing the tracer, trace_pipe will issue an EOF. We needed
+to set the ftrace tracer _before_ cating the trace_pipe file.
+
+
+trace entries
+-------------
+
+Having too much or not enough data can be troublesome in diagnosing
+some issue in the kernel. The file trace_entries is used to modify
+the size of the internal trace buffers. The numbers listed
+is the number of entries that can be recorded per CPU. To know
+the full size, multiply the number of possible CPUS with the
+number of entries.
+
+ # cat /debug/tracing/trace_entries
+65620
+
+Note, to modify this you must have tracing fulling disabled. To do that,
+echo "none" into the current_tracer.
+
+ # echo none > /debug/tracing/current_tracer
+ # echo 100000 > /debug/tracing/trace_entries
+ # cat /debug/tracing/trace_entries
+100045
+
+
+Notice that we echoed in 100,000 but the size is 100,045. The entries
+are held by individual pages. It allocates the number of pages it takes
+to fulfill the request. If more entries may fit on the last page
+it will add them.
+
+ # echo 1 > /debug/tracing/trace_entries
+ # cat /debug/tracing/trace_entries
+85
+
+This shows us that 85 entries can fit on a single page.
+
+The number of pages that will be allocated is a percentage of available
+memory. Allocating too much will produces an error.
+
+ # echo 1000000000000 > /debug/tracing/trace_entries
+-bash: echo: write error: Cannot allocate memory
+ # cat /debug/tracing/trace_entries
+85
+
diff --git a/Documentation/hwmon/ibmaem b/Documentation/hwmon/ibmaem
new file mode 100644
index 000000000000..2fefaf582a43
--- /dev/null
+++ b/Documentation/hwmon/ibmaem
@@ -0,0 +1,37 @@
+Kernel driver ibmaem
+======================
+
+Supported systems:
+  * Any recent IBM System X server with Active Energy Manager support.
+    This includes the x3350, x3550, x3650, x3655, x3755, x3850 M2,
+    x3950 M2, and certain HS2x/LS2x/QS2x blades.  The IPMI host interface
+    driver ("ipmi-si") needs to be loaded for this driver to do anything.
+    Prefix: 'ibmaem'
+    Datasheet: Not available
+
+Author: Darrick J. Wong
+
+Description
+-----------
+
+This driver implements sensor reading support for the energy and power
+meters available on various IBM System X hardware through the BMC.  All
+sensor banks will be exported as platform devices; this driver can talk
+to both v1 and v2 interfaces.  This driver is completely separate from the
+older ibmpex driver.
+
+The v1 AEM interface has a simple set of features to monitor energy use.
+There is a register that displays an estimate of raw energy consumption
+since the last BMC reset, and a power sensor that returns average power
+use over a configurable interval.
+
+The v2 AEM interface is a bit more sophisticated, being able to present
+a wider range of energy and power use registers, the power cap as
+set by the AEM software, and temperature sensors.
+
+Special Features
+----------------
+
+The "power_cap" value displays the current system power cap, as set by
+the Active Energy Manager software.  Setting the power cap from the host
+is not currently supported.
diff --git a/Documentation/hwmon/sysfs-interface b/Documentation/hwmon/sysfs-interface
index f4a8ebc1ef1a..2d845730d4e0 100644
--- a/Documentation/hwmon/sysfs-interface
+++ b/Documentation/hwmon/sysfs-interface
@@ -2,17 +2,12 @@ Naming and data format standards for sysfs files
 ------------------------------------------------
 
 The libsensors library offers an interface to the raw sensors data
-through the sysfs interface. See libsensors documentation and source for
-further information. As of writing this document, libsensors
-(from lm_sensors 2.8.3) is heavily chip-dependent. Adding or updating
-support for any given chip requires modifying the library's code.
-This is because libsensors was written for the procfs interface
-older kernel modules were using, which wasn't standardized enough.
-Recent versions of libsensors (from lm_sensors 2.8.2 and later) have
-support for the sysfs interface, though.
-
-The new sysfs interface was designed to be as chip-independent as
-possible.
+through the sysfs interface. Since lm-sensors 3.0.0, libsensors is
+completely chip-independent. It assumes that all the kernel drivers
+implement the standard sysfs interface described in this document.
+This makes adding or updating support for any given chip very easy, as
+libsensors, and applications using it, do not need to be modified.
+This is a major improvement compared to lm-sensors 2.
 
 Note that motherboards vary widely in the connections to sensor chips.
 There is no standard that ensures, for example, that the second
@@ -35,19 +30,17 @@ access this data in a simple and consistent way. That said, such programs
 will have to implement conversion, labeling and hiding of inputs. For
 this reason, it is still not recommended to bypass the library.
 
-If you are developing a userspace application please send us feedback on
-this standard.
-
-Note that this standard isn't completely established yet, so it is subject
-to changes. If you are writing a new hardware monitoring driver those
-features can't seem to fit in this interface, please contact us with your
-extension proposal. Keep in mind that backward compatibility must be
-preserved.
-
 Each chip gets its own directory in the sysfs /sys/devices tree.  To
 find all sensor chips, it is easier to follow the device symlinks from
 /sys/class/hwmon/hwmon*.
 
+Up to lm-sensors 3.0.0, libsensors looks for hardware monitoring attributes
+in the "physical" device directory. Since lm-sensors 3.0.1, attributes found
+in the hwmon "class" device directory are also supported. Complex drivers
+(e.g. drivers for multifunction chips) may want to use this possibility to
+avoid namespace pollution. The only drawback will be that older versions of
+libsensors won't support the driver in question.
+
 All sysfs values are fixed point numbers.
 
 There is only one value per file, unlike the older /proc specification.
diff --git a/Documentation/i2c/writing-clients b/Documentation/i2c/writing-clients
index ee75cbace28d..d4cd4126d1ad 100644
--- a/Documentation/i2c/writing-clients
+++ b/Documentation/i2c/writing-clients
@@ -25,12 +25,23 @@ routines, and should be zero-initialized except for fields with data you
 provide.  A client structure holds device-specific information like the
 driver model device node, and its I2C address.
 
+/* iff driver uses driver model ("new style") binding model: */
+
+static struct i2c_device_id foo_idtable[] = {
+        { "foo", my_id_for_foo },
+        { "bar", my_id_for_bar },
+        { }
+};
+
+MODULE_DEVICE_TABLE(i2c, foo_idtable);
+
 static struct i2c_driver foo_driver = {
         .driver = {
                 .name   = "foo",
         },
 
         /* iff driver uses driver model ("new style") binding model: */
+        .id_table       = foo_ids,
         .probe          = foo_probe,
         .remove         = foo_remove,
 
@@ -173,10 +184,9 @@ handle may be used during foo_probe().  If foo_probe() reports success
 (zero not a negative status code) it may save the handle and use it until
 foo_remove() returns.  That binding model is used by most Linux drivers.
 
-Drivers match devices when i2c_client.driver_name and the driver name are
-the same; this approach is used in several other busses that don't have
-device typing support in the hardware.  The driver and module name should
-match, so hotplug/coldplug mechanisms will modprobe the driver.
+The probe function is called when an entry in the id_table name field
+matches the device's name. It is passed the entry that was matched so
+the driver knows which one in the table matched.
 
 
 Device Creation (Standard driver model)
diff --git a/Documentation/kernel-doc-nano-HOWTO.txt b/Documentation/kernel-doc-nano-HOWTO.txt
index 2075c0658bf5..0bd32748a467 100644
--- a/Documentation/kernel-doc-nano-HOWTO.txt
+++ b/Documentation/kernel-doc-nano-HOWTO.txt
@@ -1,6 +1,105 @@
 kernel-doc nano-HOWTO
 =====================
 
+How to format kernel-doc comments
+---------------------------------
+
+In order to provide embedded, 'C' friendly, easy to maintain,
+but consistent and extractable documentation of the functions and
+data structures in the Linux kernel, the Linux kernel has adopted
+a consistent style for documenting functions and their parameters,
+and structures and their members.
+
+The format for this documentation is called the kernel-doc format.
+It is documented in this Documentation/kernel-doc-nano-HOWTO.txt file.
+
+This style embeds the documentation within the source files, using
+a few simple conventions.  The scripts/kernel-doc perl script, some
+SGML templates in Documentation/DocBook, and other tools understand
+these conventions, and are used to extract this embedded documentation
+into various documents.
+
+In order to provide good documentation of kernel functions and data
+structures, please use the following conventions to format your
+kernel-doc comments in Linux kernel source.
+
+We definitely need kernel-doc formatted documentation for functions
+that are exported to loadable modules using EXPORT_SYMBOL.
+
+We also look to provide kernel-doc formatted documentation for
+functions externally visible to other kernel files (not marked
+"static").
+
+We also recommend providing kernel-doc formatted documentation
+for private (file "static") routines, for consistency of kernel
+source code layout.  But this is lower priority and at the
+discretion of the MAINTAINER of that kernel source file.
+
+Data structures visible in kernel include files should also be
+documented using kernel-doc formatted comments.
+
+The opening comment mark "/**" is reserved for kernel-doc comments.
+Only comments so marked will be considered by the kernel-doc scripts,
+and any comment so marked must be in kernel-doc format.  Do not use
+"/**" to be begin a comment block unless the comment block contains
+kernel-doc formatted comments.  The closing comment marker for
+kernel-doc comments can be either "*/" or "**/".
+
+Kernel-doc comments should be placed just before the function
+or data structure being described.
+
+Example kernel-doc function comment:
+
+/**
+ * foobar() - short function description of foobar
+ * @arg1:       Describe the first argument to foobar.
+ * @arg2:       Describe the second argument to foobar.
+ *              One can provide multiple line descriptions
+ *              for arguments.
+ *
+ * A longer description, with more discussion of the function foobar()
+ * that might be useful to those using or modifying it.  Begins with
+ * empty comment line, and may include additional embedded empty
+ * comment lines.
+ *
+ * The longer description can have multiple paragraphs.
+ **/
+
+The first line, with the short description, must be on a single line.
+
+The @argument descriptions must begin on the very next line following
+this opening short function description line, with no intervening
+empty comment lines.
+
+Example kernel-doc data structure comment.
+
+/**
+ * struct blah - the basic blah structure
+ * @mem1:       describe the first member of struct blah
+ * @mem2:       describe the second member of struct blah,
+ *              perhaps with more lines and words.
+ *
+ * Longer description of this structure.
+ **/
+
+The kernel-doc function comments describe each parameter to the
+function, in order, with the @name lines.
+
+The kernel-doc data structure comments describe each structure member
+in the data structure, with the @name lines.
+
+The longer description formatting is "reflowed", losing your line
+breaks.  So presenting carefully formatted lists within these
+descriptions won't work so well; derived documentation will lose
+the formatting.
+
+See the section below "How to add extractable documentation to your
+source files" for more details and notes on how to format kernel-doc
+comments.
+
+Components of the kernel-doc system
+-----------------------------------
+
 Many places in the source tree have extractable documentation in the
 form of block comments above functions.  The components of this system
 are:
diff --git a/Documentation/kernel-docs.txt b/Documentation/kernel-docs.txt
index 5a4ef48224ae..28cdc2af2131 100644
--- a/Documentation/kernel-docs.txt
+++ b/Documentation/kernel-docs.txt
@@ -715,14 +715,14 @@
 
      * Name: "Gary's Encyclopedia - The Linux Kernel"
        Author: Gary (I suppose...).
-       URL: http://www.lisoleg.net/cgi-bin/lisoleg.pl?view=kernel.htm
-       Keywords: links, not found here?.
+       URL: http://slencyclopedia.berlios.de/index.html
+       Keywords: linux, community, everything!
        Description: Gary's Encyclopedia exists to allow the rapid finding
        of documentation and other information of interest to GNU/Linux
        users. It has about 4000 links to external pages in 150 major
        categories. This link is for kernel-specific links, documents,
-       sites... Look there if you could not find here what you were
-       looking for.
+       sites...  This list is now hosted by developer.Berlios.de,
+       but seems not to have been updated since sometime in 1999.
 
      * Name: "The home page of Linux-MM"
        Author: The Linux-MM team.
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index e07c432c731f..f22386321e7a 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -295,7 +295,7 @@ and is between 256 and 4096 characters. It is defined in the file
                         when initialising the APIC and IO-APIC components.
 
         apm=            [APM] Advanced Power Management
-                        See header of arch/i386/kernel/apm.c.
+                        See header of arch/x86/kernel/apm_32.c.
 
         arcrimi=        [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
                         Format: <io>,<irq>,<nodeID>
@@ -638,7 +638,7 @@ and is between 256 and 4096 characters. It is defined in the file
 
         elanfreq=       [X86-32]
                         See comment before function elanfreq_setup() in
-                        arch/i386/kernel/cpu/cpufreq/elanfreq.c.
+                        arch/x86/kernel/cpu/cpufreq/elanfreq.c.
 
         elevator=       [IOSCHED]
                         Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
@@ -1571,6 +1571,10 @@ and is between 256 and 4096 characters. It is defined in the file
                         Format: { parport<nr> | timid | 0 }
                         See also Documentation/parport.txt.
 
+        pmtmr=          [X86] Manual setup of pmtmr I/O Port. 
+                        Override pmtimer IOPort with a hex value.
+                        e.g. pmtmr=0x508
+
         pnpacpi=        [ACPI]
                         { off }
 
@@ -1679,6 +1683,10 @@ and is between 256 and 4096 characters. It is defined in the file
                         Format: <reboot_mode>[,<reboot_mode2>[,...]]
                         See arch/*/kernel/reboot.c or arch/*/kernel/process.c                   
 
+        relax_domain_level=
+                        [KNL, SMP] Set scheduler's default relax_domain_level.
+                        See Documentation/cpusets.txt.
+
         reserve=        [KNL,BUGS] Force the kernel to ignore some iomem area
 
         reservetop=     [X86-32]
diff --git a/Documentation/kobject.txt b/Documentation/kobject.txt
index bf3256e04027..51a8021ee532 100644
--- a/Documentation/kobject.txt
+++ b/Documentation/kobject.txt
@@ -305,7 +305,7 @@ should not be manipulated by any other user.
 
 A kset keeps its children in a standard kernel linked list.  Kobjects point
 back to their containing kset via their kset field. In almost all cases,
-the kobjects belonging to a ket have that kset (or, strictly, its embedded
+the kobjects belonging to a kset have that kset (or, strictly, its embedded
 kobject) in their parent.
 
 As a kset contains a kobject within it, it should always be dynamically
diff --git a/Documentation/laptops/thinkpad-acpi.txt b/Documentation/laptops/thinkpad-acpi.txt
index 01c6c3d8a7e3..64b3f146e4b0 100644
--- a/Documentation/laptops/thinkpad-acpi.txt
+++ b/Documentation/laptops/thinkpad-acpi.txt
@@ -503,7 +503,7 @@ generate input device EV_KEY events.
 In addition to the EV_KEY events, thinkpad-acpi may also issue EV_SW
 events for switches:
 
-SW_RADIO        T60 and later hardare rfkill rocker switch
+SW_RFKILL_ALL   T60 and later hardare rfkill rocker switch
 SW_TABLET_MODE  Tablet ThinkPads HKEY events 0x5009 and 0x500A
 
 Non hot-key ACPI HKEY event map:
diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 3be8ab2a886a..82fafe0429fe 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -157,6 +157,9 @@ struct virtqueue
 
         /* The routine to call when the Guest pings us. */
         void (*handle_output)(int fd, struct virtqueue *me);
+
+        /* Outstanding buffers */
+        unsigned int inflight;
 };
 
 /* Remember the arguments to the program so we can "reboot" */
@@ -702,6 +705,7 @@ static unsigned get_vq_desc(struct virtqueue *vq,
                         errx(1, "Looped descriptor");
         } while ((i = next_desc(vq, i)) != vq->vring.num);
 
+        vq->inflight++;
         return head;
 }
 
@@ -719,6 +723,7 @@ static void add_used(struct virtqueue *vq, unsigned int head, int len)
         /* Make sure buffer is written before we update index. */
         wmb();
         vq->vring.used->idx++;
+        vq->inflight--;
 }
 
 /* This actually sends the interrupt for this virtqueue */
@@ -726,8 +731,9 @@ static void trigger_irq(int fd, struct virtqueue *vq)
 {
         unsigned long buf[] = { LHREQ_IRQ, vq->config.irq };
 
-        /* If they don't want an interrupt, don't send one. */
-        if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+        /* If they don't want an interrupt, don't send one, unless empty. */
+        if ((vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+            && vq->inflight)
                 return;
 
         /* Send the Guest an interrupt tell them we used something up. */
@@ -1107,6 +1113,7 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs,
         vq->next = NULL;
         vq->last_avail_idx = 0;
         vq->dev = dev;
+        vq->inflight = 0;
 
         /* Initialize the configuration. */
         vq->config.num = num_descs;
@@ -1368,6 +1375,7 @@ static void setup_tun_net(const char *arg)
 
         /* Tell Guest what MAC address to use. */
         add_feature(dev, VIRTIO_NET_F_MAC);
+        add_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY);
         set_config(dev, sizeof(conf), &conf);
 
         /* We don't need the socket any more; setup is done. */
diff --git a/Documentation/networking/arcnet.txt b/Documentation/networking/arcnet.txt
index 770fc41a78e8..796012540386 100644
--- a/Documentation/networking/arcnet.txt
+++ b/Documentation/networking/arcnet.txt
@@ -46,7 +46,7 @@ These are the ARCnet drivers for Linux.
 
 
 This new release (2.91) has been put together by David Woodhouse 
-<dwmw2@cam.ac.uk>, in an attempt to tidy up the driver after adding support 
+<dwmw2@infradead.org>, in an attempt to tidy up the driver after adding support
 for yet another chipset. Now the generic support has been separated from the
 individual chipset drivers, and the source files aren't quite so packed with
 #ifdefs! I've changed this file a bit, but kept it in the first person from
diff --git a/Documentation/networking/bridge.txt b/Documentation/networking/bridge.txt
index bdae2db4119c..bec69a8a1697 100644
--- a/Documentation/networking/bridge.txt
+++ b/Documentation/networking/bridge.txt
@@ -1,6 +1,6 @@
 In order to use the Ethernet bridging functionality, you'll need the
 userspace tools. These programs and documentation are available
-at http://bridge.sourceforge.net.  The download page is
+at http://www.linux-foundation.org/en/Net:Bridge.  The download page is
 http://prdownloads.sourceforge.net/bridge.
 
 If you still have questions, don't hesitate to post to the mailing list 
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 17a6e46fbd43..946b66e1b652 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -81,23 +81,23 @@ inet_peer_minttl - INTEGER
         Minimum time-to-live of entries.  Should be enough to cover fragment
         time-to-live on the reassembling side.  This minimum time-to-live  is
         guaranteed if the pool size is less than inet_peer_threshold.
-        Measured in jiffies(1).
+        Measured in seconds.
 
 inet_peer_maxttl - INTEGER
         Maximum time-to-live of entries.  Unused entries will expire after
         this period of time if there is no memory pressure on the pool (i.e.
         when the number of entries in the pool is very small).
-        Measured in jiffies(1).
+        Measured in seconds.
 
 inet_peer_gc_mintime - INTEGER
         Minimum interval between garbage collection passes.  This interval is
         in effect under high memory pressure on the pool.
-        Measured in jiffies(1).
+        Measured in seconds.
 
 inet_peer_gc_maxtime - INTEGER
         Minimum interval between garbage collection passes.  This interval is
         in effect under low (or absent) memory pressure on the pool.
-        Measured in jiffies(1).
+        Measured in seconds.
 
 TCP variables: 
 
@@ -148,9 +148,9 @@ tcp_available_congestion_control - STRING
         but not loaded.
 
 tcp_base_mss - INTEGER
-        The initial value of search_low to be used by Packetization Layer
-        Path MTU Discovery (MTU probing).  If MTU probing is enabled,
-        this is the inital MSS used by the connection.
+        The initial value of search_low to be used by the packetization layer
+        Path MTU discovery (MTU probing).  If MTU probing is enabled,
+        this is the initial MSS used by the connection.
 
 tcp_congestion_control - STRING
         Set the congestion control algorithm to be used for new
@@ -185,10 +185,9 @@ tcp_frto - INTEGER
         timeouts.  It is particularly beneficial in wireless environments
         where packet loss is typically due to random radio interference
         rather than intermediate router congestion.  F-RTO is sender-side
-        only modification.  Therefore it does not require any support from
-        the peer, but in a typical case, however, where wireless link is
-        the local access link and most of the data flows downlink, the
-        faraway servers should have F-RTO enabled to take advantage of it.
+        only modification. Therefore it does not require any support from
+        the peer.
+
         If set to 1, basic version is enabled.  2 enables SACK enhanced
         F-RTO if flow uses SACK.  The basic version can be used also when
         SACK is in use though scenario(s) with it exists where F-RTO
@@ -276,7 +275,7 @@ tcp_mem - vector of 3 INTEGERs: min, pressure, max
         memory.
 
 tcp_moderate_rcvbuf - BOOLEAN
-        If set, TCP performs receive buffer autotuning, attempting to
+        If set, TCP performs receive buffer auto-tuning, attempting to
         automatically size the buffer (no greater than tcp_rmem[2]) to
         match the size required by the path for full throughput.  Enabled by
         default.
@@ -336,7 +335,7 @@ tcp_rmem - vector of 3 INTEGERs: min, default, max
         pressure.
         Default: 8K
 
-        default: default size of receive buffer used by TCP sockets.
+        default: initial size of receive buffer used by TCP sockets.
         This value overrides net.core.rmem_default used by other protocols.
         Default: 87380 bytes. This value results in window of 65535 with
         default setting of tcp_adv_win_scale and tcp_app_win:0 and a bit
@@ -344,8 +343,10 @@ tcp_rmem - vector of 3 INTEGERs: min, default, max
 
         max: maximal size of receive buffer allowed for automatically
         selected receiver buffers for TCP socket. This value does not override
-        net.core.rmem_max, "static" selection via SO_RCVBUF does not use this.
-        Default: 87380*2 bytes.
+        net.core.rmem_max.  Calling setsockopt() with SO_RCVBUF disables
+        automatic tuning of that socket's receive buffer size, in which
+        case this value is ignored.
+        Default: between 87380B and 4MB, depending on RAM size.
 
 tcp_sack - BOOLEAN
         Enable select acknowledgments (SACKS).
@@ -358,7 +359,7 @@ tcp_slow_start_after_idle - BOOLEAN
         Default: 1
 
 tcp_stdurg - BOOLEAN
-        Use the Host requirements interpretation of the TCP urg pointer field.
+        Use the Host requirements interpretation of the TCP urgent pointer field.
         Most hosts use the older BSD interpretation, so if you turn this on
         Linux might not communicate correctly with them.
         Default: FALSE
@@ -371,12 +372,12 @@ tcp_synack_retries - INTEGER
 tcp_syncookies - BOOLEAN
         Only valid when the kernel was compiled with CONFIG_SYNCOOKIES
         Send out syncookies when the syn backlog queue of a socket
-        overflows. This is to prevent against the common 'syn flood attack'
+        overflows. This is to prevent against the common 'SYN flood attack'
         Default: FALSE
 
         Note, that syncookies is fallback facility.
         It MUST NOT be used to help highly loaded servers to stand
-        against legal connection rate. If you see synflood warnings
+        against legal connection rate. If you see SYN flood warnings
         in your logs, but investigation shows that they occur
         because of overload with legal connections, you should tune
         another parameters until this warning disappear.
@@ -386,7 +387,7 @@ tcp_syncookies - BOOLEAN
         to use TCP extensions, can result in serious degradation
         of some services (f.e. SMTP relaying), visible not by you,
         but your clients and relays, contacting you. While you see
-        synflood warnings in logs not being really flooded, your server
+        SYN flood warnings in logs not being really flooded, your server
         is seriously misconfigured.
 
 tcp_syn_retries - INTEGER
@@ -419,19 +420,21 @@ tcp_window_scaling - BOOLEAN
         Enable window scaling as defined in RFC1323.
 
 tcp_wmem - vector of 3 INTEGERs: min, default, max
-        min: Amount of memory reserved for send buffers for TCP socket.
+        min: Amount of memory reserved for send buffers for TCP sockets.
         Each TCP socket has rights to use it due to fact of its birth.
         Default: 4K
 
-        default: Amount of memory allowed for send buffers for TCP socket
-        by default. This value overrides net.core.wmem_default used
-        by other protocols, it is usually lower than net.core.wmem_default.
+        default: initial size of send buffer used by TCP sockets.  This
+        value overrides net.core.wmem_default used by other protocols.
+        It is usually lower than net.core.wmem_default.
         Default: 16K
 
-        max: Maximal amount of memory allowed for automatically selected
-        send buffers for TCP socket. This value does not override
-        net.core.wmem_max, "static" selection via SO_SNDBUF does not use this.
-        Default: 128K
+        max: Maximal amount of memory allowed for automatically tuned
+        send buffers for TCP sockets. This value does not override
+        net.core.wmem_max.  Calling setsockopt() with SO_SNDBUF disables
+        automatic tuning of that socket's send buffer size, in which case
+        this value is ignored.
+        Default: between 64K and 4MB, depending on RAM size.
 
 tcp_workaround_signed_windows - BOOLEAN
         If set, assume no receipt of a window scaling option means the
@@ -794,10 +797,6 @@ tag - INTEGER
         Allows you to write a number, which can be used as required.
         Default value is 0.
 
-(1) Jiffie: internal timeunit for the kernel. On the i386 1/100s, on the
-Alpha 1/1024s. See the HZ define in /usr/include/asm/param.h for the exact
-value on your system. 
-
 Alexey Kuznetsov.
 kuznet@ms2.inr.ac.ru
 
@@ -1064,24 +1063,193 @@ bridge-nf-filter-pppoe-tagged - BOOLEAN
         Default: 1
 
 
-UNDOCUMENTED:
+proc/sys/net/sctp/* Variables:
+
+addip_enable - BOOLEAN
+        Enable or disable extension of  Dynamic Address Reconfiguration
+        (ADD-IP) functionality specified in RFC5061.  This extension provides
+        the ability to dynamically add and remove new addresses for the SCTP
+        associations.
+
+        1: Enable extension.
+
+        0: Disable extension.
+
+        Default: 0
+
+addip_noauth_enable - BOOLEAN
+        Dynamic Address Reconfiguration (ADD-IP) requires the use of
+        authentication to protect the operations of adding or removing new
+        addresses.  This requirement is mandated so that unauthorized hosts
+        would not be able to hijack associations.  However, older
+        implementations may not have implemented this requirement while
+        allowing the ADD-IP extension.  For reasons of interoperability,
+        we provide this variable to control the enforcement of the
+        authentication requirement.
+
+        1: Allow ADD-IP extension to be used without authentication.  This
+           should only be set in a closed environment for interoperability
+           with older implementations.
+
+        0: Enforce the authentication requirement
+
+        Default: 0
+
+auth_enable - BOOLEAN
+        Enable or disable Authenticated Chunks extension.  This extension
+        provides the ability to send and receive authenticated chunks and is
+        required for secure operation of Dynamic Address Reconfiguration
+        (ADD-IP) extension.
+
+        1: Enable this extension.
+        0: Disable this extension.
+
+        Default: 0
+
+prsctp_enable - BOOLEAN
+        Enable or disable the Partial Reliability extension (RFC3758) which
+        is used to notify peers that a given DATA should no longer be expected.
+
+        1: Enable extension
+        0: Disable
+
+        Default: 1
+
+max_burst - INTEGER
+        The limit of the number of new packets that can be initially sent.  It
+        controls how bursty the generated traffic can be.
+
+        Default: 4
+
+association_max_retrans - INTEGER
+        Set the maximum number for retransmissions that an association can
+        attempt deciding that the remote end is unreachable.  If this value
+        is exceeded, the association is terminated.
+
+        Default: 10
+
+max_init_retransmits - INTEGER
+        The maximum number of retransmissions of INIT and COOKIE-ECHO chunks
+        that an association will attempt before declaring the destination
+        unreachable and terminating.
+
+        Default: 8
+
+path_max_retrans - INTEGER
+        The maximum number of retransmissions that will be attempted on a given
+        path.  Once this threshold is exceeded, the path is considered
+        unreachable, and new traffic will use a different path when the
+        association is multihomed.
+
+        Default: 5
+
+rto_initial - INTEGER
+        The initial round trip timeout value in milliseconds that will be used
+        in calculating round trip times.  This is the initial time interval
+        for retransmissions.
 
-dev_weight FIXME
-discovery_slots FIXME
-discovery_timeout FIXME
-fast_poll_increase FIXME
-ip6_queue_maxlen FIXME
-lap_keepalive_time FIXME
-lo_cong FIXME
-max_baud_rate FIXME
-max_dgram_qlen FIXME
-max_noreply_time FIXME
-max_tx_data_size FIXME
-max_tx_window FIXME
-min_tx_turn_time FIXME
-mod_cong FIXME
-no_cong FIXME
-no_cong_thresh FIXME
-slot_timeout FIXME
-warn_noreply_time FIXME
+        Default: 3000
+
+rto_max - INTEGER
+        The maximum value (in milliseconds) of the round trip timeout.  This
+        is the largest time interval that can elapse between retransmissions.
+
+        Default: 60000
+
+rto_min - INTEGER
+        The minimum value (in milliseconds) of the round trip timeout.  This
+        is the smallest time interval the can elapse between retransmissions.
+
+        Default: 1000
+
+hb_interval - INTEGER
+        The interval (in milliseconds) between HEARTBEAT chunks.  These chunks
+        are sent at the specified interval on idle paths to probe the state of
+        a given path between 2 associations.
+
+        Default: 30000
+
+sack_timeout - INTEGER
+        The amount of time (in milliseconds) that the implementation will wait
+        to send a SACK.
+
+        Default: 200
+
+valid_cookie_life - INTEGER
+        The default lifetime of the SCTP cookie (in milliseconds).  The cookie
+        is used during association establishment.
+
+        Default: 60000
+
+cookie_preserve_enable - BOOLEAN
+        Enable or disable the ability to extend the lifetime of the SCTP cookie
+        that is used during the establishment phase of SCTP association
+
+        1: Enable cookie lifetime extension.
+        0: Disable
+
+        Default: 1
+
+rcvbuf_policy - INTEGER
+        Determines if the receive buffer is attributed to the socket or to
+        association.   SCTP supports the capability to create multiple
+        associations on a single socket.  When using this capability, it is
+        possible that a single stalled association that's buffering a lot
+        of data may block other associations from delivering their data by
+        consuming all of the receive buffer space.  To work around this,
+        the rcvbuf_policy could be set to attribute the receiver buffer space
+        to each association instead of the socket.  This prevents the described
+        blocking.
+
+        1: rcvbuf space is per association
+        0: recbuf space is per socket
+
+        Default: 0
+
+sndbuf_policy - INTEGER
+        Similar to rcvbuf_policy above, this applies to send buffer space.
+
+        1: Send buffer is tracked per association
+        0: Send buffer is tracked per socket.
+
+        Default: 0
+
+sctp_mem - vector of 3 INTEGERs: min, pressure, max
+        Number of pages allowed for queueing by all SCTP sockets.
+
+        min: Below this number of pages SCTP is not bothered about its
+        memory appetite. When amount of memory allocated by SCTP exceeds
+        this number, SCTP starts to moderate memory usage.
+
+        pressure: This value was introduced to follow format of tcp_mem.
+
+        max: Number of pages allowed for queueing by all SCTP sockets.
+
+        Default is calculated at boot time from amount of available memory.
+
+sctp_rmem - vector of 3 INTEGERs: min, default, max
+        See tcp_rmem for a description.
+
+sctp_wmem  - vector of 3 INTEGERs: min, default, max
+        See tcp_wmem for a description.
+
+UNDOCUMENTED:
 
+/proc/sys/net/core/*
+        dev_weight FIXME
+
+/proc/sys/net/unix/*
+        max_dgram_qlen FIXME
+
+/proc/sys/net/irda/*
+        fast_poll_increase FIXME
+        warn_noreply_time FIXME
+        discovery_slots FIXME
+        slot_timeout FIXME
+        max_baud_rate FIXME
+        discovery_timeout FIXME
+        lap_keepalive_time FIXME
+        max_noreply_time FIXME
+        max_tx_data_size FIXME
+        max_tx_window FIXME
+        min_tx_turn_time FIXME
diff --git a/Documentation/networking/s2io.txt b/Documentation/networking/s2io.txt
index 4bde53e85f3f..1e28e2ddb90a 100644
--- a/Documentation/networking/s2io.txt
+++ b/Documentation/networking/s2io.txt
@@ -83,9 +83,9 @@ Valid range: Limited by memory on system
 Default: 30 
 
 e. intr_type
-Specifies interrupt type. Possible values 1(INTA), 2(MSI), 3(MSI-X)
-Valid range: 1-3
-Default: 1 
+Specifies interrupt type. Possible values 0(INTA), 2(MSI-X)
+Valid values: 0, 2
+Default: 2
 
 5.  Performance suggestions
 General:
diff --git a/Documentation/video4linux/CARDLIST.au0828 b/Documentation/video4linux/CARDLIST.au0828
index aaae360312e4..86d1c8e7b18f 100644
--- a/Documentation/video4linux/CARDLIST.au0828
+++ b/Documentation/video4linux/CARDLIST.au0828
@@ -1,4 +1,4 @@
   0 -> Unknown board                            (au0828)
-  1 -> Hauppauge HVR950Q                        (au0828)        [2040:7200]
+  1 -> Hauppauge HVR950Q                        (au0828)        [2040:7200,2040:7210,2040:7217,2040:721b,2040:721f,2040:7280,0fd9:0008]
   2 -> Hauppauge HVR850                         (au0828)        [2040:7240]
   3 -> DViCO FusionHDTV USB                     (au0828)        [0fe9:d620]
diff --git a/Documentation/video4linux/CARDLIST.cx88 b/Documentation/video4linux/CARDLIST.cx88
index 543957346469..7cf5685d3645 100644
--- a/Documentation/video4linux/CARDLIST.cx88
+++ b/Documentation/video4linux/CARDLIST.cx88
@@ -60,7 +60,7 @@
  59 -> DViCO FusionHDTV 5 PCI nano                         [18ac:d530]
  60 -> Pinnacle Hybrid PCTV                                [12ab:1788]
  61 -> Winfast TV2000 XP Global                            [107d:6f18]
- 62 -> PowerColor Real Angel 330                           [14f1:ea3d]
+ 62 -> PowerColor RA330                                    [14f1:ea3d]
  63 -> Geniatech X8000-MT DVBT                             [14f1:8852]
  64 -> DViCO FusionHDTV DVB-T PRO                          [18ac:db30]
  65 -> DViCO FusionHDTV 7 Gold                             [18ac:d610]
diff --git a/Documentation/video4linux/cx18.txt b/Documentation/video4linux/cx18.txt
index 077d56ec3f3d..6842c262890f 100644
--- a/Documentation/video4linux/cx18.txt
+++ b/Documentation/video4linux/cx18.txt
@@ -1,7 +1,9 @@
 Some notes regarding the cx18 driver for the Conexant CX23418 MPEG
 encoder chip:
 
-1) The only hardware currently supported is the Hauppauge HVR-1600.
+1) The only hardware currently supported is the Hauppauge HVR-1600
+   card and the Compro VideoMate H900 (note that this card only
+   supports analog input, it has no digital tuner!).
 
 2) Some people have problems getting the i2c bus to work. Cause unknown.
    The symptom is that the eeprom cannot be read and the card is
diff --git a/Documentation/vm/pagemap.txt b/Documentation/vm/pagemap.txt
new file mode 100644
index 000000000000..ce72c0fe6177
--- /dev/null
+++ b/Documentation/vm/pagemap.txt
@@ -0,0 +1,77 @@
+pagemap, from the userspace perspective
+---------------------------------------
+
+pagemap is a new (as of 2.6.25) set of interfaces in the kernel that allow
+userspace programs to examine the page tables and related information by
+reading files in /proc.
+
+There are three components to pagemap:
+
+ * /proc/pid/pagemap.  This file lets a userspace process find out which
+   physical frame each virtual page is mapped to.  It contains one 64-bit
+   value for each virtual page, containing the following data (from
+   fs/proc/task_mmu.c, above pagemap_read):
+
+    * Bits 0-55  page frame number (PFN) if present
+    * Bits 0-4   swap type if swapped
+    * Bits 5-55  swap offset if swapped
+    * Bits 55-60 page shift (page size = 1<<page shift)
+    * Bit  61    reserved for future use
+    * Bit  62    page swapped
+    * Bit  63    page present
+
+   If the page is not present but in swap, then the PFN contains an
+   encoding of the swap file number and the page's offset into the
+   swap. Unmapped pages return a null PFN. This allows determining
+   precisely which pages are mapped (or in swap) and comparing mapped
+   pages between processes.
+
+   Efficient users of this interface will use /proc/pid/maps to
+   determine which areas of memory are actually mapped and llseek to
+   skip over unmapped regions.
+
+ * /proc/kpagecount.  This file contains a 64-bit count of the number of
+   times each page is mapped, indexed by PFN.
+
+ * /proc/kpageflags.  This file contains a 64-bit set of flags for each
+   page, indexed by PFN.
+
+   The flags are (from fs/proc/proc_misc, above kpageflags_read):
+
+     0. LOCKED
+     1. ERROR
+     2. REFERENCED
+     3. UPTODATE
+     4. DIRTY
+     5. LRU
+     6. ACTIVE
+     7. SLAB
+     8. WRITEBACK
+     9. RECLAIM
+    10. BUDDY
+
+Using pagemap to do something useful:
+
+The general procedure for using pagemap to find out about a process' memory
+usage goes like this:
+
+ 1. Read /proc/pid/maps to determine which parts of the memory space are
+    mapped to what.
+ 2. Select the maps you are interested in -- all of them, or a particular
+    library, or the stack or the heap, etc.
+ 3. Open /proc/pid/pagemap and seek to the pages you would like to examine.
+ 4. Read a u64 for each page from pagemap.
+ 5. Open /proc/kpagecount and/or /proc/kpageflags.  For each PFN you just
+    read, seek to that entry in the file, and read the data you want.
+
+For example, to find the "unique set size" (USS), which is the amount of
+memory that a process is using that is not shared with any other process,
+you can go through every map in the process, find the PFNs, look those up
+in kpagecount, and tally up the number of pages that are only referenced
+once.
+
+Other notes:
+
+Reading from any of the files will return -EINVAL if you are not starting
+the read on an 8-byte boundary (e.g., if you seeked an odd number of bytes
+into the file), or if the size of the read is not a multiple of 8 bytes.
diff --git a/Documentation/vm/slabinfo.c b/Documentation/vm/slabinfo.c
index e4230ed16ee7..df3227605d59 100644
--- a/Documentation/vm/slabinfo.c
+++ b/Documentation/vm/slabinfo.c
@@ -1,7 +1,7 @@
 /*
  * Slabinfo: Tool to get reports about slabs
  *
- * (C) 2007 sgi, Christoph Lameter <clameter@sgi.com>
+ * (C) 2007 sgi, Christoph Lameter
  *
  * Compile by:
  *
@@ -99,7 +99,7 @@ void fatal(const char *x, ...)
 
 void usage(void)
 {
-        printf("slabinfo 5/7/2007. (c) 2007 sgi. clameter@sgi.com\n\n"
+        printf("slabinfo 5/7/2007. (c) 2007 sgi.\n\n"
                 "slabinfo [-ahnpvtsz] [-d debugopts] [slab-regexp]\n"
                 "-a|--aliases           Show aliases\n"
                 "-A|--activity          Most active slabs first\n"
diff --git a/Documentation/vm/slub.txt b/Documentation/vm/slub.txt
index 7c13f22a0c9e..bb1f5c6e28b3 100644
--- a/Documentation/vm/slub.txt
+++ b/Documentation/vm/slub.txt
@@ -266,4 +266,4 @@ of other objects.
 
         slub_debug=FZ,dentry
 
-Christoph Lameter, <clameter@sgi.com>, May 30, 2007
+Christoph Lameter, May 30, 2007