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  1. 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
  3. 26 Feb, 2010 2 commits
  5. 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
  7. 24 Feb, 2010 13 commits
  9. 23 Feb, 2010 15 commits
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