Merge tag 'trace-3.10' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "Along with the usual minor fixes and clean ups there are a few major
  changes with this pull request.

   1) Multiple buffers for the ftrace facility

  This feature has been requested by many people over the last few
  years.  I even heard that Google was about to implement it themselves.
  I finally had time and cleaned up the code such that you can now
  create multiple instances of the ftrace buffer and have different
  events go to different buffers.  This way, a low frequency event will
  not be lost in the noise of a high frequency event.

  Note, currently only events can go to different buffers, the tracers
  (ie function, function_graph and the latency tracers) still can only
  be written to the main buffer.

   2) The function tracer triggers have now been extended.

  The function tracer had two triggers.  One to enable tracing when a
  function is hit, and one to disable tracing.  Now you can record a
  stack trace on a single (or many) function(s), take a snapshot of the
  buffer (copy it to the snapshot buffer), and you can enable or disable
  an event to be traced when a function is hit.

   3) A perf clock has been added.

  A "perf" clock can be chosen to be used when tracing.  This will cause
  ftrace to use the same clock as perf uses, and hopefully this will
  make it easier to interleave the perf and ftrace data for analysis."

* tag 'trace-3.10' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (82 commits)
  tracepoints: Prevent null probe from being added
  tracing: Compare to 1 instead of zero for is_signed_type()
  tracing: Remove obsolete macro guard _TRACE_PROFILE_INIT
  ftrace: Get rid of ftrace_profile_bits
  tracing: Check return value of tracing_init_dentry()
  tracing: Get rid of unneeded key calculation in ftrace_hash_move()
  tracing: Reset ftrace_graph_filter_enabled if count is zero
  tracing: Fix off-by-one on allocating stat->pages
  kernel: tracing: Use strlcpy instead of strncpy
  tracing: Update debugfs README file
  tracing: Fix ftrace_dump()
  tracing: Rename trace_event_mutex to trace_event_sem
  tracing: Fix comment about prefix in arch_syscall_match_sym_name()
  tracing: Convert trace_destroy_fields() to static
  tracing: Move find_event_field() into trace_events.c
  tracing: Use TRACE_MAX_PRINT instead of constant
  tracing: Use pr_warn_once instead of open coded implementation
  ring-buffer: Add ring buffer startup selftest
  tracing: Bring Documentation/trace/ftrace.txt up to date
  tracing: Add "perf" trace_clock
  ...

Conflicts:
	kernel/trace/ftrace.c
	kernel/trace/trace.c

1 files changed, 49 insertions, 0 deletions

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index fc382d6e2765..5e9efd4b83a4 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -176,6 +176,8 @@ config IRQSOFF_TRACER
         select GENERIC_TRACER
         select TRACER_MAX_TRACE
         select RING_BUFFER_ALLOW_SWAP
+        select TRACER_SNAPSHOT
+        select TRACER_SNAPSHOT_PER_CPU_SWAP
         help
           This option measures the time spent in irqs-off critical
           sections, with microsecond accuracy.
@@ -198,6 +200,8 @@ config PREEMPT_TRACER
         select GENERIC_TRACER
         select TRACER_MAX_TRACE
         select RING_BUFFER_ALLOW_SWAP
+        select TRACER_SNAPSHOT
+        select TRACER_SNAPSHOT_PER_CPU_SWAP
         help
           This option measures the time spent in preemption-off critical
           sections, with microsecond accuracy.
@@ -217,6 +221,7 @@ config SCHED_TRACER
         select GENERIC_TRACER
         select CONTEXT_SWITCH_TRACER
         select TRACER_MAX_TRACE
+        select TRACER_SNAPSHOT
         help
           This tracer tracks the latency of the highest priority task
           to be scheduled in, starting from the point it has woken up.
@@ -248,6 +253,27 @@ config TRACER_SNAPSHOT
               echo 1 > /sys/kernel/debug/tracing/snapshot
               cat snapshot
 
+config TRACER_SNAPSHOT_PER_CPU_SWAP
+        bool "Allow snapshot to swap per CPU"
+        depends on TRACER_SNAPSHOT
+        select RING_BUFFER_ALLOW_SWAP
+        help
+          Allow doing a snapshot of a single CPU buffer instead of a
+          full swap (all buffers). If this is set, then the following is
+          allowed:
+
+              echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
+
+          After which, only the tracing buffer for CPU 2 was swapped with
+          the main tracing buffer, and the other CPU buffers remain the same.
+
+          When this is enabled, this adds a little more overhead to the
+          trace recording, as it needs to add some checks to synchronize
+          recording with swaps. But this does not affect the performance
+          of the overall system. This is enabled by default when the preempt
+          or irq latency tracers are enabled, as those need to swap as well
+          and already adds the overhead (plus a lot more).
+
 config TRACE_BRANCH_PROFILING
         bool
         select GENERIC_TRACER
@@ -524,6 +550,29 @@ config RING_BUFFER_BENCHMARK
 
           If unsure, say N.
 
+config RING_BUFFER_STARTUP_TEST
+       bool "Ring buffer startup self test"
+       depends on RING_BUFFER
+       help
+         Run a simple self test on the ring buffer on boot up. Late in the
+         kernel boot sequence, the test will start that kicks off
+         a thread per cpu. Each thread will write various size events
+         into the ring buffer. Another thread is created to send IPIs
+         to each of the threads, where the IPI handler will also write
+         to the ring buffer, to test/stress the nesting ability.
+         If any anomalies are discovered, a warning will be displayed
+         and all ring buffers will be disabled.
+
+         The test runs for 10 seconds. This will slow your boot time
+         by at least 10 more seconds.
+
+         At the end of the test, statics and more checks are done.
+         It will output the stats of each per cpu buffer. What
+         was written, the sizes, what was read, what was lost, and
+         other similar details.
+
+         If unsure, say N
+
 endif # FTRACE
 
 endif # TRACING_SUPPORT