Re: [GIT PULL 00/11] perf/core improvements and fixes

[Ingo Molnar]

* Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:

> Hi Ingo,
> 
> 	Please consider pulling,
> 
> - Arnaldo
> 
> The following changes since commit 675965b00d734c985e4285f5bec7e524d15fc4e1:
> 
>   perf: Export perf_event_sysfs_show() (2016-02-29 09:35:27 +0100)
> 
> are available in the git repository at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git tags/perf-core-for-mingo-20160229
> 
> for you to fetch changes up to 575a02e00b11eecbbabcb1eb22eab4c68e91ae77:
> 
>   perf record: Ensure return non-zero rc when mmap fail (2016-02-29 12:44:15 -0300)
> 
> ----------------------------------------------------------------
> perf/core improvements and fixes:
> 
> User visible:
> 
> - Check existence of frontend/backed stalled cycles in 'perf stat' (Andi Kleen)
> 
> - Avoid installing .o files from tools/lib/ into the python extension (Jiri Olsa)
> 
> - Rename the tracepoint '/format' field that carries the syscall ID from 'nr',
>   that is also the name of some syscalls arguments, to "__syscall_nr", to
>   avoid having multiple fields with the same name, that was breaking the
>   python script skeleton generator from perf.data files (Taeung Song)
> 
> - Support converting data from bpf events in 'perf data' (Wang Nan)
> 
> Infrastructure:
> 
> - Split libtraceevent's pevent_print_event() (Steven Rostedt)
> 
> - Librarize some 'perf record' bits to allow handling multiple perf.data
>   files per session (Wang Nan)
> 
> - Ensure return non-zero rc when mmap fail in 'perf record' (Wang Nan)
> 
> Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> 
> ----------------------------------------------------------------
> Andi Kleen (1):
>       perf stat: Check existence of frontend/backed stalled cycles

> 
> Jiri Olsa (1):
>       perf tools: Fix python extension build
> 
> Steven Rostedt (1):
>       tools lib traceevent: Split pevent_print_event() into specific functionality functions
> 
> Taeung Song (2):
>       perf trace: Check and discard not only 'nr' but also '__syscall_nr'
>       tracing/syscalls: Rename "/format" tracepoint field name "nr" to "__syscall_nr:
> 
> Wang Nan (6):
>       perf data: Support converting data from bpf_perf_event_output()
>       perf data: Explicitly set byte order for integer types
>       perf record: Use WARN_ONCE to replace 'if' condition
>       perf record: Extract synthesize code to record__synthesize()
>       perf record: Introduce record__finish_output() to finish a perf.data
>       perf record: Ensure return non-zero rc when mmap fail
> 
>  kernel/trace/trace_syscalls.c      |  16 ++--
>  tools/lib/traceevent/event-parse.c | 136 +++++++++++++++++++++++-------
>  tools/lib/traceevent/event-parse.h |  13 +++
>  tools/perf/builtin-record.c        | 168 ++++++++++++++++++++++---------------
>  tools/perf/builtin-stat.c          |  22 ++++-
>  tools/perf/builtin-trace.c         |   8 +-
>  tools/perf/util/data-convert-bt.c  | 118 +++++++++++++++++++++++++-
>  tools/perf/util/setup.py           |   4 +
>  8 files changed, 372 insertions(+), 113 deletions(-)

Hm, there's a 'perf stat' regression that I can see:

Before:

 triton:~/tip> perf stat -a sleep 1

 Performance counter stats for 'system wide':

      11990.023100      task-clock (msec)         #   11.981 CPUs utilized          
             8,802      context-switches          #    0.734 K/sec                  
               543      cpu-migrations            #    0.045 K/sec                  
            97,375      page-faults               #    0.008 M/sec                  
     9,854,385,894      cycles                    #    0.822 GHz                    
    15,274,841,152      stalled-cycles-frontend   #  155.01% frontend cycles idle   
   <not supported>      stalled-cycles-backend   
     9,634,486,137      instructions              #    0.98  insn per cycle         
                                                  #    1.59  stalled cycles per insn
     1,818,488,088      branches                  #  151.667 M/sec                  
        46,365,120      branch-misses             #    2.55% of all branches        

       1.000741599 seconds time elapsed

After:

 triton:~/tip> perf stat -a sleep 1

 Performance counter stats for 'system wide':

      11989.280397      task-clock (msec)         #   11.981 CPUs utilized          
              1299      context-switches          #    0.108 K/sec                  
                 6      cpu-migrations            #    0.001 K/sec                  
                70      page-faults               #    0.006 K/sec                  
         127008602      cycles                    #    0.011 GHz                    
         279538533      stalled-cycles-frontend   #  220.09% frontend cycles idle   
         119213269      instructions              #    0.94  insn per cycle         
                                                  #    2.34  stalled cycles per insn
          24166678      branches                  #    2.016 M/sec                  
            505681      branch-misses             #    2.09% of all branches        

       1.000684278 seconds time elapsed


... see how the numbers became human-unreadable, losing the big-number separator?

I suspect it's due to the following commit:

  fa184776ac27 perf stat: Check existence of frontend/backed stalled cycles

Thanks,

	Ingo