[tip:perfcounters/core] perf record: Disable profiling before draining the buffer

tip-bot for Peter Zijlstra
2009-09-17T18:08:20Z

Commit-ID: 5abfd8bf28feeb633afdea2309fb0927d17606be
Gitweb: http://git.kernel.org/tip/5abfd8bf28feeb633afdea2309fb0927d17606be
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Thu, 17 Sep 2009 19:59:05 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 17 Sep 2009 20:02:47 +0200

perf record: Disable profiling before draining the buffer

I noticed that perf-record continues profiling itself after the
child terminated and we're draining the buffer.

This can cause a _lot_ of overhead with --all recording - we keep
and keep recording, which produces new and new events.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
tools/perf/builtin-record.c | 13 ++++++++++++-
1 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 5f3127e..2459e5a 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -524,6 +524,7 @@ static int __cmd_record(int argc, const char **argv)
pid_t pid = 0;
int flags;
int ret;
+ unsigned long waking = 0;

page_size = sysconf(_SC_PAGE_SIZE);
nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
@@ -634,10 +635,20 @@ static int __cmd_record(int argc, const char **argv)
if (hits == samples) {
if (done)
break;
- ret = poll(event_array, nr_poll, 100);
+ ret = poll(event_array, nr_poll, -1);
+ waking++;
+ }
+
+ if (done) {
+ for (i = 0; i < nr_cpu; i++) {
+ for (counter = 0; counter < nr_counters; counter++)
+ ioctl(fd[i][counter], PERF_COUNTER_IOC_DISABLE);
+ }
}
}

+ fprintf(stderr, "[ perf record: Woken up %ld times to write data ]\n", waking);
+
/*
* Approximate RIP event size: 24 bytes.
*/