Re: [GIT PULL 0/8] Annotation weekly ponies delivery

[Peter Zijlstra <peterz@infradead.org>]

On Sat, 2012-05-12 at 13:40 -0700, Linus Torvalds wrote:
> The whole "-e cycles:pp" doesn't work any more. I don't get any nice
> PEBS information, I get the totally useless irq-based profiling.
> 
> The difference for a "make -j" profile is quite stunning:
> 
> Doing "perf record -f -e cycles:pp -F 20000 make -j"
> 
>  - my current git:
> 
>     [ perf record: Woken up 47 times to write data ]
>     [ perf record: Captured and wrote 11.890 MB perf.data (~519462 samples) ]
> 
>  - with the above tree pulled into my current git tree (but compiling
> the same old tree):
> 
>     [ perf record: Woken up 1 times to write data ]
>     [ perf record: Captured and wrote 0.031 MB perf.data (~1375 samples) ] 

The output simply suggests we're not getting enough samples not that
PEBS isn't working, in fact I can could reproduce without using PEBS.

This bisected to the below commit, the code has since been changed again
and all that evlist stuff gives me a head-ache. Acme, Namhyung ?


55261f46702cec96911a81aacfb3cba13434d304 is the first bad commit
commit 55261f46702cec96911a81aacfb3cba13434d304
Author: Namhyung Kim <namhyung.kim@lge.com>
Date:   Mon May 7 14:08:59 2012 +0900

    perf evlist: Fix creation of cpu map
    
    Currently, 'perf record -- sleep 1' creates a cpu map for all online
    cpus since it turns out calling cpu_map__new(NULL). Fix it.
    
    Also it is guaranteed that cpu_list is NULL if PID/TID is given by
    calling perf_target__validate(), so we can make the conditional bit
    simpler.
    
    This also fixes perf test 7 (Validate) failure on my 6 core machine:
    
      $ cat /sys/devices/system/cpu/online
      0-11
      $ ./perf test -v 7
       7: Validate PERF_RECORD_* events & perf_sample fields:
      --- start ---
      perf_evlist__mmap: Operation not permitted
      ---- end ----
      Validate PERF_RECORD_* events & perf_sample fields: FAILED!
    
    Signed-off-by: Namhyung Kim <namhyung.kim@lge.com>
    Reviewed-by: David Ahern <dsahern@gmail.com>
    Cc: David Ahern <dsahern@gmail.com>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Namhyung Kim <namhyung@gmail.com>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Link: http://lkml.kernel.org/r/1336367344-28071-3-git-send-email-namhyung.kim@lge.com
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>