5 files changed, 47 insertions, 41 deletions

diff --git a/Documentation/scheduler/00-INDEX b/Documentation/scheduler/00-INDEX
index 3c00c9c3219e..d2651c47ae27 100644
--- a/Documentation/scheduler/00-INDEX
+++ b/Documentation/scheduler/00-INDEX
@@ -3,7 +3,7 @@
 sched-arch.txt
         - CPU Scheduler implementation hints for architecture specific code.
 sched-design-CFS.txt
-        - goals, design and implementation of the Complete Fair Scheduler.
+        - goals, design and implementation of the Completely Fair Scheduler.
 sched-domains.txt
         - information on scheduling domains.
 sched-nice-design.txt
diff --git a/Documentation/scheduler/sched-design-CFS.txt b/Documentation/scheduler/sched-design-CFS.txt
index 8239ebbcddce..91ecff07cede 100644
--- a/Documentation/scheduler/sched-design-CFS.txt
+++ b/Documentation/scheduler/sched-design-CFS.txt
@@ -164,7 +164,7 @@ This is the (partial) list of the hooks:
    It puts the scheduling entity (task) into the red-black tree and
    increments the nr_running variable.
 
- - dequeue_tree(...)
+ - dequeue_task(...)
 
    When a task is no longer runnable, this function is called to keep the
    corresponding scheduling entity out of the red-black tree.  It decrements
@@ -195,11 +195,6 @@ This is the (partial) list of the hooks:
    This function is mostly called from time tick functions; it might lead to
    process switch.  This drives the running preemption.
 
- - task_new(...)
-
-   The core scheduler gives the scheduling module an opportunity to manage new
-   task startup.  The CFS scheduling module uses it for group scheduling, while
-   the scheduling module for a real-time task does not use it.
 
 
 
@@ -228,9 +223,10 @@ When CONFIG_FAIR_GROUP_SCHED is defined, a "cpu.shares" file is created for each
 group created using the pseudo filesystem.  See example steps below to create
 task groups and modify their CPU share using the "cgroups" pseudo filesystem.
 
-        # mkdir /dev/cpuctl
-        # mount -t cgroup -ocpu none /dev/cpuctl
-        # cd /dev/cpuctl
+        # mount -t tmpfs cgroup_root /sys/fs/cgroup
+        # mkdir /sys/fs/cgroup/cpu
+        # mount -t cgroup -ocpu none /sys/fs/cgroup/cpu
+        # cd /sys/fs/cgroup/cpu
 
         # mkdir multimedia      # create "multimedia" group of tasks
         # mkdir browser         # create "browser" group of tasks
diff --git a/Documentation/scheduler/sched-domains.txt b/Documentation/scheduler/sched-domains.txt
index 373ceacc367e..b7ee379b651b 100644
--- a/Documentation/scheduler/sched-domains.txt
+++ b/Documentation/scheduler/sched-domains.txt
@@ -1,8 +1,7 @@
-Each CPU has a "base" scheduling domain (struct sched_domain). These are
-accessed via cpu_sched_domain(i) and this_sched_domain() macros. The domain
+Each CPU has a "base" scheduling domain (struct sched_domain). The domain
 hierarchy is built from these base domains via the ->parent pointer. ->parent
-MUST be NULL terminated, and domain structures should be per-CPU as they
-are locklessly updated.
+MUST be NULL terminated, and domain structures should be per-CPU as they are
+locklessly updated.
 
 Each scheduling domain spans a number of CPUs (stored in the ->span field).
 A domain's span MUST be a superset of it child's span (this restriction could
@@ -26,11 +25,26 @@ is treated as one entity. The load of a group is defined as the sum of the
 load of each of its member CPUs, and only when the load of a group becomes
 out of balance are tasks moved between groups.
 
-In kernel/sched.c, rebalance_tick is run periodically on each CPU. This
-function takes its CPU's base sched domain and checks to see if has reached
-its rebalance interval. If so, then it will run load_balance on that domain.
-rebalance_tick then checks the parent sched_domain (if it exists), and the
-parent of the parent and so forth.
+In kernel/sched.c, trigger_load_balance() is run periodically on each CPU
+through scheduler_tick(). It raises a softirq after the next regularly scheduled
+rebalancing event for the current runqueue has arrived. The actual load
+balancing workhorse, run_rebalance_domains()->rebalance_domains(), is then run
+in softirq context (SCHED_SOFTIRQ).
+
+The latter function takes two arguments: the current CPU and whether it was idle
+at the time the scheduler_tick() happened and iterates over all sched domains
+our CPU is on, starting from its base domain and going up the ->parent chain.
+While doing that, it checks to see if the current domain has exhausted its
+rebalance interval. If so, it runs load_balance() on that domain. It then checks
+the parent sched_domain (if it exists), and the parent of the parent and so
+forth.
+
+Initially, load_balance() finds the busiest group in the current sched domain.
+If it succeeds, it looks for the busiest runqueue of all the CPUs' runqueues in
+that group. If it manages to find such a runqueue, it locks both our initial
+CPU's runqueue and the newly found busiest one and starts moving tasks from it
+to our runqueue. The exact number of tasks amounts to an imbalance previously
+computed while iterating over this sched domain's groups.
 
 *** Implementing sched domains ***
 The "base" domain will "span" the first level of the hierarchy. In the case
diff --git a/Documentation/scheduler/sched-rt-group.txt b/Documentation/scheduler/sched-rt-group.txt
index 605b0d40329d..71b54d549987 100644
--- a/Documentation/scheduler/sched-rt-group.txt
+++ b/Documentation/scheduler/sched-rt-group.txt
@@ -129,9 +129,8 @@ priority!
 Enabling CONFIG_RT_GROUP_SCHED lets you explicitly allocate real
 CPU bandwidth to task groups.
 
-This uses the /cgroup virtual file system and
-"/cgroup/<cgroup>/cpu.rt_runtime_us" to control the CPU time reserved for each
-control group.
+This uses the cgroup virtual file system and "<cgroup>/cpu.rt_runtime_us"
+to control the CPU time reserved for each control group.
 
 For more information on working with control groups, you should read
 Documentation/cgroups/cgroups.txt as well.
@@ -150,7 +149,7 @@ For now, this can be simplified to just the following (but see Future plans):
 ===============
 
 There is work in progress to make the scheduling period for each group
-("/cgroup/<cgroup>/cpu.rt_period_us") configurable as well.
+("<cgroup>/cpu.rt_period_us") configurable as well.
 
 The constraint on the period is that a subgroup must have a smaller or
 equal period to its parent. But realistically its not very useful _yet_
diff --git a/Documentation/scheduler/sched-stats.txt b/Documentation/scheduler/sched-stats.txt
index 01e69404ee5e..1cd5d51bc761 100644
--- a/Documentation/scheduler/sched-stats.txt
+++ b/Documentation/scheduler/sched-stats.txt
@@ -1,3 +1,7 @@
+Version 15 of schedstats dropped counters for some sched_yield:
+yld_exp_empty, yld_act_empty and yld_both_empty. Otherwise, it is
+identical to version 14.
+
 Version 14 of schedstats includes support for sched_domains, which hit the
 mainline kernel in 2.6.20 although it is identical to the stats from version
 12 which was in the kernel from 2.6.13-2.6.19 (version 13 never saw a kernel
@@ -28,32 +32,25 @@ to write their own scripts, the fields are described here.
 
 CPU statistics
 --------------
-cpu<N> 1 2 3 4 5 6 7 8 9 10 11 12
-
-NOTE: In the sched_yield() statistics, the active queue is considered empty
-    if it has only one process in it, since obviously the process calling
-    sched_yield() is that process.
+cpu<N> 1 2 3 4 5 6 7 8 9
 
-First four fields are sched_yield() statistics:
-     1) # of times both the active and the expired queue were empty
-     2) # of times just the active queue was empty
-     3) # of times just the expired queue was empty
-     4) # of times sched_yield() was called
+First field is a sched_yield() statistic:
+     1) # of times sched_yield() was called
 
 Next three are schedule() statistics:
-     5) # of times we switched to the expired queue and reused it
-     6) # of times schedule() was called
-     7) # of times schedule() left the processor idle
+     2) # of times we switched to the expired queue and reused it
+     3) # of times schedule() was called
+     4) # of times schedule() left the processor idle
 
 Next two are try_to_wake_up() statistics:
-     8) # of times try_to_wake_up() was called
-     9) # of times try_to_wake_up() was called to wake up the local cpu
+     5) # of times try_to_wake_up() was called
+     6) # of times try_to_wake_up() was called to wake up the local cpu
 
 Next three are statistics describing scheduling latency:
-    10) sum of all time spent running by tasks on this processor (in jiffies)
-    11) sum of all time spent waiting to run by tasks on this processor (in
+     7) sum of all time spent running by tasks on this processor (in jiffies)
+     8) sum of all time spent waiting to run by tasks on this processor (in
         jiffies)
-    12) # of timeslices run on this cpu
+     9) # of timeslices run on this cpu
 
 
 Domain statistics