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authorStephane Eranian <eranian@google.com>2012-02-21 18:54:25 +0400
committerArnaldo Carvalho de Melo <acme@redhat.com>2012-02-21 21:05:43 +0400
commit6b1bee9035d430c4b4f586df6df4b3f840e89b5b (patch)
treed386e6bd537c7e8c338ec0af1aa9672e1470f233 /tools/perf/util/thread_map.c
parentdfd3b1e3e8a580bcbf854d46ae0f22c8333e82d8 (diff)
downloadlinux-6b1bee9035d430c4b4f586df6df4b3f840e89b5b.tar.xz
perf tools: fix broken perf record -a mode
The following commit: b52956c perf tools: Allow multiple threads or processes in record, stat, top introduced a bug in the thread_map code which caused perf record -a to not setup system-wide monitoring properly. $ taskset -c 1 noploop 1000 & $ perf record -a -C 1 sleep 10 $ perf report -D | tail -20 cycles stats: TOTAL events: 4413 MMAP events: 4025 COMM events: 340 SAMPLE events: 48 Here I was expecting about 10,000 samples and not 48. In system-wide mode, the PID passed to perf_event_open() must be -1 and it was 0. That caused the kernel to setup a per-process event on PID:0. Consequently, the number of samples captured does not correspond to the requested measurement. The following one-liner fixes the problem for me with or without -C. I would also suggest to change the malloc() to something that matches the struct definition. thread_map->map[] is declared as int map[] and not pid_t map[]. If map[] can only contain pids, then change the struct definition. Acked-by: David Ahern <dsahern@gmail.com> Cc: David Ahern <dsahern@gmail.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20120221145424.GA6757@quad Signed-off-by: Stephane Eranian <eranian@google.com> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/thread_map.c')
-rw-r--r--tools/perf/util/thread_map.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/perf/util/thread_map.c b/tools/perf/util/thread_map.c
index e15983cf077d..84d9bd782004 100644
--- a/tools/perf/util/thread_map.c
+++ b/tools/perf/util/thread_map.c
@@ -229,7 +229,7 @@ static struct thread_map *thread_map__new_by_tid_str(const char *tid_str)
if (!tid_str) {
threads = malloc(sizeof(*threads) + sizeof(pid_t));
if (threads != NULL) {
- threads->map[1] = -1;
+ threads->map[0] = -1;
threads->nr = 1;
}
return threads;