linux-kernel - Re: [PATCH] perf: Fix 0 count issue of cpu-clock

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Message-ID: <20251118105006.GO3245006@noisy.programming.kicks-ass.net>
Date: Tue, 18 Nov 2025 11:50:06 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Dapeng Mi <dapeng1.mi@...ux.intel.com>
Cc: Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>, Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Andi Kleen <ak@...ux.intel.com>,
	Eranian Stephane <eranian@...gle.com>, linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org, Dapeng Mi <dapeng1.mi@...el.com>,
	Zide Chen <zide.chen@...el.com>,
	Falcon Thomas <thomas.falcon@...el.com>,
	Xudong Hao <xudong.hao@...el.com>
Subject: Re: [PATCH] perf: Fix 0 count issue of cpu-clock

On Wed, Nov 12, 2025 at 04:05:26PM +0800, Dapeng Mi wrote:
> 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. Besides, or flags with PERF_EF_UPDATE
> for task-clock although currently the flags argument would always be 0.
> 
> Fixes: bc4394e5e79c ("perf: Fix the throttle error of some clock events")
> Signed-off-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
> ---

So I'm forever struggling to find what tree a particular commit is in,
but afaict the above fingered commit is already in Linus' tree and so
this should go to perf/urgent, right?