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  1. 06 Mar, 2010 4 commits
    • Tim Bird's avatar
      function-graph: Add tracing_thresh support to function_graph tracer · 0e950173
      Tim Bird authored 
      Add support for tracing_thresh to the function_graph tracer.  This
version of this feature isolates the checks into new entry and
return functions, to avoid adding more conditional code into the
main function_graph paths.

When the tracing_thresh is set and the function graph tracer is
enabled, only the functions that took longer than the time in
microseconds that was set in tracing_thresh are recorded. To do this
efficiently, only the function exits are recorded:

 [tracing]# echo 100 > tracing_thresh
 [tracing]# echo function_graph > current_tracer
 [tracing]# cat trace
 # tracer: function_graph
 #
 # CPU  DURATION                  FUNCTION CALLS
 # |     |   |                     |   |   |   |
  1) ! 119.214 us  |  } /* smp_apic_timer_interrupt */
  1)   <========== |
  0) ! 101.527 us  |              } /* __rcu_process_callbacks */
  0) ! 126.461 us  |            } /* rcu_process_callbacks */
  0) ! 145.111 us  |          } /* __do_softirq */
  0) ! 149.667 us  |        } /* do_softirq */
  0) ! 168.817 us  |      } /* irq_exit */
  0) ! 248.254 us  |    } /* smp_apic_timer_interrupt */

Also, add support for specifying tracing_thresh on the kernel
command line.  When used like so: "tracing_thresh=200 ftrace=function_graph"
this can be used to analyse system startup.  It is important to disable
tracing soon after boot, in order to avoid losing the trace data.
Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: default avatarTim Bird <tim.bird@am.sony.com>
LKML-Reference: <4B87098B.4040308@am.sony.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      0e950173
    • Arnaldo Carvalho de Melo's avatar
      tracing: Update the comm field in the right variable in update_max_tr · 1acaa1b2
      Arnaldo Carvalho de Melo authored 
      The latency output showed:

 #    | task: -3 (uid:0 nice:0 policy:1 rt_prio:99)

The comm is missing in the "task:" and it looks like a minus 3 is
the output. The correct display should be:

 #    | task: migration/0-3 (uid:0 nice:0 policy:1 rt_prio:99)

The problem is that the comm is being stored in the wrong data
structure. The max_tr.data[cpu] is what stores the comm, not the
tr->data[cpu].

Before this patch the max_tr.data[cpu]->comm was zeroed and the /debug/trace
ended up showing just the '-' sign followed by the pid.

Also remove a needless initialization of max_data.
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <1267824230-23861-1-git-send-email-acme@infradead.org>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      1acaa1b2
    • Steven Rostedt's avatar
      function-graph: Use comment notation for func names of dangling '}' · a094fe04
      Steven Rostedt authored 
      When a '}' does not have a matching function start, the name is printed
within parenthesis. But this makes it confusing between ending '}'
and function starts. This patch makes the function name appear in C comment
notation.

Old view:
 3)   1.281 us    |            } (might_fault)
 3)   3.620 us    |          } (filldir)
 3)   5.251 us    |        } (call_filldir)
 3)               |        call_filldir() {
 3)               |          filldir() {

New view:
 3)   1.281 us    |            } /* might_fault */
 3)   3.620 us    |          } /* filldir */
 3)   5.251 us    |        } /* call_filldir */
 3)               |        call_filldir() {
 3)               |          filldir() {
Requested-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      a094fe04
    • Steven Rostedt's avatar
      function-graph: Fix unused reference to ftrace_set_func() · 801c29fd
      Steven Rostedt authored 
      The declaration of ftrace_set_func() is at the start of the ftrace.c file
and wrapped with a #ifdef CONFIG_FUNCTION_GRAPH condition. If function
graph tracing is enabled but CONFIG_DYNAMIC_FTRACE is not, a warning
about that function being declared static and unused is given.

This really should have been placed within the CONFIG_FUNCTION_GRAPH
condition that uses ftrace_set_func().

Moving the declaration down fixes the warning and makes the code cleaner.
Reported-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      801c29fd
  3. 28 Feb, 2010 1 commit
    • Frederic Weisbecker's avatar
      tracing: Include irqflags headers from trace clock · ae1f3038
      Frederic Weisbecker authored 
      trace_clock.c includes spinlock.h, which ends up including
asm/system.h, which in turn includes linux/irqflags.h in x86.

So the definition of raw_local_irq_save is luckily covered there,
but this is not the case in parisc:

   tip/kernel/trace/trace_clock.c:86: error: implicit declaration of function 'raw_local_irq_save'
   tip/kernel/trace/trace_clock.c:112: error: implicit declaration of function 'raw_local_irq_restore'

We need to include linux/irqflags.h directly from trace_clock.c
to avoid such build error.
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      ae1f3038
  5. 27 Feb, 2010 3 commits
    • Ingo Molnar's avatar
      Merge branch 'tip/tracing/core' of... · 48091742
      Ingo Molnar authored 
      Merge branch 'tip/tracing/core' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/core
      48091742
    • Ingo Molnar's avatar
      Merge branch 'tracing/core' of... · 6fb83029
      Ingo Molnar authored 
      Merge branch 'tracing/core' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing into tracing/core
      6fb83029
    • Steven Rostedt's avatar
      ftrace: Add function names to dangling } in function graph tracer · f1c7f517
      Steven Rostedt authored 
      The function graph tracer is currently the most invasive tracer
in the ftrace family. It can easily overflow the buffer even with
10megs per CPU. This means that events can often be lost.

On start up, or after events are lost, if the function return is
recorded but the function enter was lost, all we get to see is the
exiting '}'.

Here is how a typical trace output starts:

 [tracing] cat trace
 # tracer: function_graph
 #
 # CPU  DURATION                  FUNCTION CALLS
 # |     |   |                     |   |   |   |
  0) + 91.897 us   |                  }
  0) ! 567.961 us  |                }
  0)   <========== |
  0) ! 579.083 us  |                _raw_spin_lock_irqsave();
  0)   4.694 us    |                _raw_spin_unlock_irqrestore();
  0) ! 594.862 us  |              }
  0) ! 603.361 us  |            }
  0) ! 613.574 us  |          }
  0) ! 623.554 us  |        }
  0)   3.653 us    |        fget_light();
  0)               |        sock_poll() {

There are a series of '}' with no matching "func() {". There's no information
to what functions these ending brackets belong to.

This patch adds a stack on the per cpu structure used in outputting
the function graph tracer to keep track of what function was outputted.
Then on a function exit event, it checks the depth to see if the
function exit has a matching entry event. If it does, then it only
prints the '}', otherwise it adds the function name after the '}'.

This allows function exit events to show what function they belong to
at trace output startup, when the entry was lost due to ring buffer
overflow, or even after a new task is scheduled in.

Here is what the above trace will look like after this patch:

 [tracing] cat trace
 # tracer: function_graph
 #
 # CPU  DURATION                  FUNCTION CALLS
 # |     |   |                     |   |   |   |
  0) + 91.897 us   |                  } (irq_exit)
  0) ! 567.961 us  |                } (smp_apic_timer_interrupt)
  0)   <========== |
  0) ! 579.083 us  |                _raw_spin_lock_irqsave();
  0)   4.694 us    |                _raw_spin_unlock_irqrestore();
  0) ! 594.862 us  |              } (add_wait_queue)
  0) ! 603.361 us  |            } (__pollwait)
  0) ! 613.574 us  |          } (tcp_poll)
  0) ! 623.554 us  |        } (sock_poll)
  0)   3.653 us    |        fget_light();
  0)               |        sock_poll() {
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      f1c7f517
  7. 26 Feb, 2010 2 commits
  9. 25 Feb, 2010 7 commits
    • Wenji Huang's avatar
      tracing: Simplify memory recycle of trace_define_field · 7b60997f
      Wenji Huang authored 
      Discard freeing field->type since it is not necessary.
Reviewed-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Signed-off-by: default avatarWenji Huang <wenji.huang@oracle.com>
LKML-Reference: <1266997226-6833-5-git-send-email-wenji.huang@oracle.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      7b60997f
    • Wenji Huang's avatar
      tracing: Remove unnecessary variable in print_graph_return · c85f3a91
      Wenji Huang authored 
      The "cpu" variable is declared at the start of the function and
also within a branch, with the exact same initialization.

Remove the local variable of the same name in the branch.
Signed-off-by: default avatarWenji Huang <wenji.huang@oracle.com>
LKML-Reference: <1266997226-6833-3-git-send-email-wenji.huang@oracle.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      c85f3a91
    • Wenji Huang's avatar
      tracing: Fix typo of info text in trace_kprobe.c · a5efd925
      Wenji Huang authored 
      Signed-off-by: default avatarWenji Huang <wenji.huang@oracle.com>
LKML-Reference: <1266997226-6833-2-git-send-email-wenji.huang@oracle.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      a5efd925
    • Wenji Huang's avatar
      tracing: Fix typo in prof_sysexit_enable() · 6574658b
      Wenji Huang authored 
      Signed-off-by: default avatarWenji Huang <wenji.huang@oracle.com>
LKML-Reference: <1266997226-6833-1-git-send-email-wenji.huang@oracle.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      6574658b
    • Li Zefan's avatar
      tracing: Remove CONFIG_TRACE_POWER from kernel config · 1ab83a89
      Li Zefan authored 
      The power tracer has been converted to power trace events.
Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4B84D50E.4070806@cn.fujitsu.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      1ab83a89
    • Jeff Mahoney's avatar
      tracing: Fix ftrace_event_call alignment for use with gcc 4.5 · 86c38a31
      Jeff Mahoney authored 
      GCC 4.5 introduces behavior that forces the alignment of structures to
 use the largest possible value. The default value is 32 bytes, so if
 some structures are defined with a 4-byte alignment and others aren't
 declared with an alignment constraint at all - it will align at 32-bytes.

 For things like the ftrace events, this results in a non-standard array.
 When initializing the ftrace subsystem, we traverse the _ftrace_events
 section and call the initialization callback for each event. When the
 structures are misaligned, we could be treating another part of the
 structure (or the zeroed out space between them) as a function pointer.

 This patch forces the alignment for all the ftrace_event_call structures
 to 4 bytes.

 Without this patch, the kernel fails to boot very early when built with
 gcc 4.5.

 It's trivial to check the alignment of the members of the array, so it
 might be worthwhile to add something to the build system to do that
 automatically. Unfortunately, that only covers this case. I've asked one
 of the gcc developers about adding a warning when this condition is seen.

Cc: stable@kernel.org
Signed-off-by: default avatarJeff Mahoney <jeffm@suse.com>
LKML-Reference: <4B85770B.6010901@suse.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      86c38a31
    • Steven Rostedt's avatar
      ftrace: Remove memory barriers from NMI code when not needed · 0c54dd34
      Steven Rostedt authored 
      The code in stop_machine that modifies the kernel text has a bit
of logic to handle the case of NMIs. stop_machine does not prevent
NMIs from executing, and if an NMI were to trigger on another CPU
as the modifying CPU is changing the NMI text, a GPF could result.

To prevent the GPF, the NMI calls ftrace_nmi_enter() which may
modify the code first, then any other NMIs will just change the
text to the same content which will do no harm. The code that
stop_machine called must wait for NMIs to finish while it changes
each location in the kernel. That code may also change the text
to what the NMI changed it to. The key is that the text will never
change content while another CPU is executing it.

To make the above work, the call to ftrace_nmi_enter() must also
do a smp_mb() as well as atomic_inc().  But for applications like
perf that require a high number of NMIs for profiling, this can have
a dramatic effect on the system. Not only is it doing a full memory
barrier on both nmi_enter() as well as nmi_exit() it is also
modifying a global variable with an atomic operation. This kills
performance on large SMP machines.

Since the memory barriers are only needed when ftrace is in the
process of modifying the text (which is seldom), this patch
adds a "modifying_code" variable that gets set before stop machine
is executed and cleared afterwards.

The NMIs will check this variable and store it in a per CPU
"save_modifying_code" variable that it will use to check if it
needs to do the memory barriers and atomic dec on NMI exit.
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      0c54dd34
  11. 24 Feb, 2010 13 commits
  13. 23 Feb, 2010 10 commits
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