• Arnaldo Carvalho de Melo's avatar
    perf header: Fixup reading of HEADER_NRCPUS feature · 835199c0
    Arnaldo Carvalho de Melo authored
    [ Upstream commit caa47047 ]
    
    The original patch introducing this header wrote the number of CPUs available
    and online in one order and then swapped those values when reading, fix it.
    
    Before:
    
      # perf record usleep 1
      # perf report --header-only | grep 'nrcpus \(online\|avail\)'
      # nrcpus online : 4
      # nrcpus avail : 4
      # echo 0 > /sys/devices/system/cpu/cpu2/online
      # perf record usleep 1
      # perf report --header-only | grep 'nrcpus \(online\|avail\)'
      # nrcpus online : 4
      # nrcpus avail : 3
      # echo 0 > /sys/devices/system/cpu/cpu1/online
      # perf record usleep 1
      # perf report --header-only | grep 'nrcpus \(online\|avail\)'
      # nrcpus online : 4
      # nrcpus avail : 2
    
    After the fix, bringing back the CPUs online:
    
      # perf report --header-only | grep 'nrcpus \(online\|avail\)'
      # nrcpus online : 2
      # nrcpus avail : 4
      # echo 1 > /sys/devices/system/cpu/cpu2/online
      # perf record usleep 1
      # perf report --header-only | grep 'nrcpus \(online\|avail\)'
      # nrcpus online : 3
      # nrcpus avail : 4
      # echo 1 > /sys/devices/system/cpu/cpu1/online
      # perf record usleep 1
      # perf report --header-only | grep 'nrcpus \(online\|avail\)'
      # nrcpus online : 4
      # nrcpus avail : 4
    Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
    Cc: Adrian Hunter <adrian.hunter@intel.com>
    Cc: Borislav Petkov <bp@suse.de>
    Cc: David Ahern <dsahern@gmail.com>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Jiri Olsa <jolsa@kernel.org>
    Cc: Kan Liang <kan.liang@intel.com>
    Cc: Stephane Eranian <eranian@google.com>
    Cc: Wang Nan <wangnan0@huawei.com>
    Fixes: fbe96f29 ("perf tools: Make perf.data more self-descriptive (v8)")
    Link: http://lkml.kernel.org/r/20150911153323.GP23511@kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
    835199c0
header.c 67.4 KB