linux-kernel - [PATCH V4 02/16] perf: Only dump the throttle log for the leader

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250520181644.2673067-3-kan.liang@linux.intel.com>
Date: Tue, 20 May 2025 11:16:30 -0700
From: kan.liang@...ux.intel.com
To: peterz@...radead.org,
	mingo@...hat.com,
	namhyung@...nel.org,
	irogers@...gle.com,
	mark.rutland@....com,
	linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org
Cc: eranian@...gle.com,
	ctshao@...gle.com,
	tmricht@...ux.ibm.com,
	leo.yan@....com,
	Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH V4 02/16] perf: Only dump the throttle log for the leader

From: Kan Liang <kan.liang@...ux.intel.com>

The PERF_RECORD_THROTTLE records are dumped for all throttled events.
It's not necessary for group events, which are throttled altogether.

Optimize it by only dump the throttle log for the leader.

The sample right after the THROTTLE record must be generated by the
actual target event. It is good enough for the perf tool to locate the
actual target event.

Suggested-by: Namhyung Kim <namhyung@...nel.org>
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
 kernel/events/core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 915698f47682..cd559501cfbd 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2744,14 +2744,16 @@ static void perf_event_unthrottle(struct perf_event *event, bool start)
 	event->hw.interrupts = 0;
 	if (start)
 		event->pmu->start(event, 0);
-	perf_log_throttle(event, 1);
+	if (event == event->group_leader)
+		perf_log_throttle(event, 1);
 }
 
 static void perf_event_throttle(struct perf_event *event)
 {
 	event->pmu->stop(event, 0);
 	event->hw.interrupts = MAX_INTERRUPTS;
-	perf_log_throttle(event, 0);
+	if (event == event->group_leader)
+		perf_log_throttle(event, 0);
 }
 
 static void perf_event_unthrottle_group(struct perf_event *event, bool skip_start_event)
-- 
2.38.1