| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.14 07/79] perf header: Fixup reading of HEADER_NRCPUS feature | Date | Sat, 17 Oct 2015 19:04:59 -0700 |
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3.14-stable review patch. If anyone has any objections, please let me know.
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From: Arnaldo Carvalho de Melo <acme@redhat.com>
commit caa470475d9b59eeff093ae650800d34612c4379 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: Namhyung 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: fbe96f29ce4b ("perf tools: Make perf.data more self-descriptive (v8)") Link: http://lkml.kernel.org/r/20150911153323.GP23511@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- tools/perf/util/header.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/tools/perf/util/header.c +++ b/tools/perf/util/header.c @@ -1715,7 +1715,7 @@ static int process_nrcpus(struct perf_fi if (ph->needs_swap) nr = bswap_32(nr); - ph->env.nr_cpus_online = nr; + ph->env.nr_cpus_avail = nr; ret = readn(fd, &nr, sizeof(nr)); if (ret != sizeof(nr)) @@ -1724,7 +1724,7 @@ static int process_nrcpus(struct perf_fi if (ph->needs_swap) nr = bswap_32(nr); - ph->env.nr_cpus_avail = nr; + ph->env.nr_cpus_online = nr; return 0; }
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