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Date:   Wed, 15 Jun 2022 01:29:55 +0000
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From:   "Yajun Deng" <yajun.deng@linux.dev>
Message-ID: <f1cdd17717cef7ec33af096e104db03c@linux.dev>
Subject: Re: [PATCH] perf/core: fix perf_event_mux_interval_ms when set
 zero
To:     "Namhyung Kim" <namhyung@kernel.org>
Cc:     "Peter Zijlstra" <peterz@infradead.org>,
        "Ingo Molnar" <mingo@redhat.com>,
        "Arnaldo Carvalho de Melo" <acme@kernel.org>,
        "Mark Rutland" <mark.rutland@arm.com>,
        "Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
        "Jiri Olsa" <jolsa@kernel.org>,
        "Stephane Eranian" <eranian@google.com>,
        "linux-perf-users" <linux-perf-users@vger.kernel.org>,
        "linux-kernel" <linux-kernel@vger.kernel.org>
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 <20220614103751.1395645-1-yajun.deng@linux.dev>
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June 15, 2022 6:08 AM, "Namhyung Kim" <namhyung@kernel.org> wrote:=0A=0A>=
 Hello,=0A> =0A> On Tue, Jun 14, 2022 at 3:38 AM Yajun Deng <yajun.deng@l=
inux.dev> wrote:=0A> =0A>> The perf_event_mux_interval_ms is set to zero =
or one by default.=0A> =0A> I see that __perf_mux_hrtimer_init() sets it =
to PERF_CPU_HRTIMER=0A> if it's less than 1.=0A> =0AYes, pmu->hrtimer_int=
erval_ms was set to PERF_CPU_HRTIMER, but perf_event_mux_interval_ms didn=
't.=0AWe can execute 'cat /sys/devices/intel_pt/perf_event_mux_interval_m=
s' see that.=0A=0A> Thanks,=0A> Namhyung=0A> =0A>> It can't change back w=
hen someone changes it from zero to another=0A>> value.=0A>> =0A>> Make p=
erf_event_mux_interval_ms to PERF_CPU_HRTIMER when set zero.=0A>> =0A>> F=
ixes: 62b856397927 ("perf: Add sysfs entry to adjust multiplexing interva=
l per PMU")=0A>> Signed-off-by: Yajun Deng <yajun.deng@linux.dev>=0A>> --=
-=0A>> kernel/events/core.c | 5 ++++-=0A>> 1 file changed, 4 insertions(+=
), 1 deletion(-)=0A>> =0A>> diff --git a/kernel/events/core.c b/kernel/ev=
ents/core.c=0A>> index 61ad10862c21..73c8c7462bbf 100644=0A>> --- a/kerne=
l/events/core.c=0A>> +++ b/kernel/events/core.c=0A>> @@ -10954,9 +10954,1=
2 @@ perf_event_mux_interval_ms_store(struct device *dev,=0A>> if (ret)=
=0A>> return ret;=0A>> =0A>> - if (timer < 1)=0A>> + if (timer < 0)=0A>> =
return -EINVAL;=0A>> =0A>> + if (timer < 1)=0A>> + timer =3D PERF_CPU_HRT=
IMER;=0A>> +=0A>> /* same value, noting to do */=0A>> if (timer =3D=3D pm=
u->hrtimer_interval_ms)=0A>> return count;=0A>> --=0A>> 2.25.1