linux-kernel - [tip: perf/urgent] perf: Fix 0 count issue of cpu-clock

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Message-ID: <176363207041.498.7734531032867658405.tip-bot2@tip-bot2>
Date: Thu, 20 Nov 2025 09:47:50 -0000
From: "tip-bot2 for Dapeng Mi" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Dapeng Mi <dapeng1.mi@...ux.intel.com>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>,
 Ian Rogers <irogers@...gle.com>, Namhyung Kim <namhyung@...nel.org>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: perf/urgent] perf: Fix 0 count issue of cpu-clock

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     f1f96511b1c4c33e53f05909dd267878e0643a9a
Gitweb:        https://git.kernel.org/tip/f1f96511b1c4c33e53f05909dd267878e0643a9a
Author:        Dapeng Mi <dapeng1.mi@...ux.intel.com>
AuthorDate:    Wed, 12 Nov 2025 16:05:26 +08:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Thu, 20 Nov 2025 10:42:12 +01:00

perf: Fix 0 count issue of cpu-clock

Currently cpu-clock event always returns 0 count, e.g.,

perf stat -e cpu-clock -- sleep 1

 Performance counter stats for 'sleep 1':
                 0      cpu-clock                        #    0.000 CPUs utilized
       1.002308394 seconds time elapsed

The root cause is the commit 'bc4394e5e79c ("perf: Fix the throttle
 error of some clock events")' adds PERF_EF_UPDATE flag check before
calling cpu_clock_event_update() to update the count, however the
PERF_EF_UPDATE flag is never set when the cpu-clock event is stopped in
counting mode (pmu->dev() -> cpu_clock_event_del() ->
cpu_clock_event_stop()). This leads to the cpu-clock event count is
never updated.

To fix this issue, force to set PERF_EF_UPDATE flag for cpu-clock event
just like what task-clock does.

Fixes: bc4394e5e79c ("perf: Fix the throttle error of some clock events")
Signed-off-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Ian Rogers <irogers@...gle.com>
Acked-by: Namhyung Kim <namhyung@...nel.org>
Link: https://patch.msgid.link/20251112080526.3971392-1-dapeng1.mi@linux.intel.com
---
 kernel/events/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1fd347d..2c35acc 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -11901,7 +11901,7 @@ static int cpu_clock_event_add(struct perf_event *event, int flags)
 
 static void cpu_clock_event_del(struct perf_event *event, int flags)
 {
-	cpu_clock_event_stop(event, flags);
+	cpu_clock_event_stop(event, PERF_EF_UPDATE);
 }
 
 static void cpu_clock_event_read(struct perf_event *event)