Messages in this thread Patch in this message | | | From | Ben Hutchings <> | Date | Fri, 09 Oct 2015 01:12:28 +0100 | Subject | [PATCH 3.2 071/107] perf header: Fixup reading of HEADER_NRCPUS feature |
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3.2.72-rc1 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> [bwh: Backported to 3.2: print_nrcpus() reads and prints these fields immediately, so read both of them into an array before printing them in reverse order.] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- 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 @@ -796,25 +796,19 @@ static void print_cpudesc(struct perf_he static void print_nrcpus(struct perf_header *ph, int fd, FILE *fp) { ssize_t ret; - u32 nr; + u32 nr[2]; ret = read(fd, &nr, sizeof(nr)); if (ret != (ssize_t)sizeof(nr)) - nr = -1; /* interpreted as error */ + nr[0] = nr[1] = -1; /* interpreted as error */ - if (ph->needs_swap) - nr = bswap_32(nr); + if (ph->needs_swap) { + nr[0] = bswap_32(nr[0]); + nr[1] = bswap_32(nr[1]); + } - fprintf(fp, "# nrcpus online : %u\n", nr); - - ret = read(fd, &nr, sizeof(nr)); - if (ret != (ssize_t)sizeof(nr)) - nr = -1; /* interpreted as error */ - - if (ph->needs_swap) - nr = bswap_32(nr); - - fprintf(fp, "# nrcpus avail : %u\n", nr); + fprintf(fp, "# nrcpus online : %u\n", nr[1]); + fprintf(fp, "# nrcpus avail : %u\n", nr[0]); } static void print_version(struct perf_header *ph, int fd, FILE *fp)
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