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

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Date:	Thu, 17 Sep 2009 18:07:48 GMT
From:	tip-bot for Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	a.p.zijlstra@...llo.nl, tglx@...utronix.de, mingo@...e.hu
Subject: [tip:perfcounters/core] perf record: Disable profiling before draining the buffer

Commit-ID:  5abfd8bf28feeb633afdea2309fb0927d17606be
Gitweb:     http://git.kernel.org/tip/5abfd8bf28feeb633afdea2309fb0927d17606be
Author:     Peter Zijlstra <a.p.zijlstra@...llo.nl>
AuthorDate: Thu, 17 Sep 2009 19:59:05 +0200
Committer:  Ingo Molnar <mingo@...e.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@...llo.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@...e.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.
 	 */
--
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