• Arnaldo Carvalho de Melo's avatar
    perf header: Fixup reading of HEADER_NRCPUS feature · bb37a2ec
    Arnaldo Carvalho de Melo authored
    commit caa47047 upstream.
    
    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 avatarJiri Slaby <jslaby@suse.cz>
    bb37a2ec
header.c 66.4 KB