Skip to content

L
linux
Switch branch/tag
  1. 06 Feb, 2013 15 commits
  3. 03 Feb, 2013 1 commit
  5. 01 Feb, 2013 2 commits
    • Steven Rostedt (Red Hat)'s avatar
      tracing: Init current_trace to nop_trace and remove NULL checks · d840f718
      Steven Rostedt (Red Hat) authored 
      On early boot up, when the ftrace ring buffer is initialized, the
static variable current_trace is initialized to &nop_trace.
Before this initialization, current_trace is NULL and will never
become NULL again. It is always reassigned to a ftrace tracer.

Several places check if current_trace is NULL before it uses
it, and this check is frivolous, because at the point in time
when the checks are made the only way current_trace could be
NULL is if ftrace failed its allocations at boot up, and the
paths to these locations would probably not be possible.

By initializing current_trace to &nop_trace where it is declared,
current_trace will never be NULL, and we can remove all these
checks of current_trace being NULL which never needed to be
checked in the first place.

Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Hiraku Toyooka <hiraku.toyooka.gu@hitachi.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      d840f718
    • Ingo Molnar's avatar
      Merge tag 'perf-core-for-mingo' of... · 9c4c5fd9
      Ingo Molnar authored 
      Merge tag 'perf-core-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core

Pull perf/core improvements and fixes from Arnaldo Carvalho de Melo:

. Make some POWER7 events available in sysfs, equivalent to
  what was done on x86, from Sukadev Bhattiprolu.

. Add event group view, from Namyung Kim:

  To use it, 'perf record' should group events when recording. And then perf
  report parses the saved group relation from file header and prints them
  together if --group option is provided.  You can use 'perf evlist' command to
  see event group information:

    $ perf record -e '{ref-cycles,cycles}' noploop 1
    [ perf record: Woken up 2 times to write data ]
    [ perf record: Captured and wrote 0.385 MB perf.data (~16807 samples) ]

    $ perf evlist --group
    {ref-cycles,cycles}

  With this example, default perf report will show you each event
  separately like this:

    $ perf report
    ...
    # group: {ref-cycles,cycles}
    # ========
    # Samples: 3K of event 'ref-cycles'
    # Event count (approx.): 3153797218
    #
    # Overhead  Command      Shared Object                      Symbol
    # ........  .......  .................  ..........................
        99.84%  noploop  noploop            [.] main
         0.07%  noploop  ld-2.15.so         [.] strcmp
         0.03%  noploop  [kernel.kallsyms]  [k] timerqueue_del
         0.03%  noploop  [kernel.kallsyms]  [k] sched_clock_cpu
         0.02%  noploop  [kernel.kallsyms]  [k] account_user_time
         0.01%  noploop  [kernel.kallsyms]  [k] __alloc_pages_nodemask
         0.00%  noploop  [kernel.kallsyms]  [k] native_write_msr_safe

    # Samples: 3K of event 'cycles'
    # Event count (approx.): 3722310525
    #
    # Overhead  Command      Shared Object                     Symbol
    # ........  .......  .................  .........................
        99.76%  noploop  noploop            [.] main
         0.11%  noploop  [kernel.kallsyms]  [k] _raw_spin_lock
         0.06%  noploop  [kernel.kallsyms]  [k] find_get_page
         0.03%  noploop  [kernel.kallsyms]  [k] sched_clock_cpu
         0.02%  noploop  [kernel.kallsyms]  [k] rcu_check_callbacks
         0.02%  noploop  [kernel.kallsyms]  [k] __current_kernel_time
         0.00%  noploop  [kernel.kallsyms]  [k] native_write_msr_safe

  In this case the event group information will be shown in the end of
  header area.  So you can use --group option to enable event group view.

    $ perf report --group
    ...
    # group: {ref-cycles,cycles}
    # ========
    # Samples: 7K of event 'anon group { ref-cycles, cycles }'
    # Event count (approx.): 6876107743
    #
    #         Overhead  Command      Shared Object                      Symbol
    # ................  .......  .................  ..........................
        99.84%  99.76%  noploop  noploop            [.] main
         0.07%   0.00%  noploop  ld-2.15.so         [.] strcmp
         0.03%   0.00%  noploop  [kernel.kallsyms]  [k] timerqueue_del
         0.03%   0.03%  noploop  [kernel.kallsyms]  [k] sched_clock_cpu
         0.02%   0.00%  noploop  [kernel.kallsyms]  [k] account_user_time
         0.01%   0.00%  noploop  [kernel.kallsyms]  [k] __alloc_pages_nodemask
         0.00%   0.00%  noploop  [kernel.kallsyms]  [k] native_write_msr_safe
         0.00%   0.11%  noploop  [kernel.kallsyms]  [k] _raw_spin_lock
         0.00%   0.06%  noploop  [kernel.kallsyms]  [k] find_get_page
         0.00%   0.02%  noploop  [kernel.kallsyms]  [k] rcu_check_callbacks
         0.00%   0.02%  noploop  [kernel.kallsyms]  [k] __current_kernel_time

  As you can see the Overhead column now contains both of ref-cycles and
  cycles and header line shows group information also - 'anon group {
  ref-cycles, cycles }'.  The output is sorted by period of group leader
  first.

  If perf.data file doesn't contain group information, this --group
  option does nothing.  So if you want enable event group view by
  default you can set it in ~/.perfconfig file:

    $ cat ~/.perfconfig
    [report]
    group = true

  It can be overridden with command line if you want:

    $ perf report --no-group
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      9c4c5fd9
  7. 31 Jan, 2013 22 commits
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7