linux-kernel - Re: [PATCH] perf/x86: Fix open counting event error

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Message-ID: <1d1cb14f-5729-4200-af20-d66b4feebe94@linux.intel.com>
Date: Thu, 24 Apr 2025 13:15:27 -0400
From: "Liang, Kan" <kan.liang@...ux.intel.com>
To: Ravi Bangoria <ravi.bangoria@....com>,
 Luo Gengkun <luogengkun@...weicloud.com>,
 "peterz@...radead.org" <peterz@...radead.org>
Cc: "mingo@...hat.com" <mingo@...hat.com>, "acme@...nel.org"
 <acme@...nel.org>, "namhyung@...nel.org" <namhyung@...nel.org>,
 "mark.rutland@....com" <mark.rutland@....com>,
 "alexander.shishkin@...ux.intel.com" <alexander.shishkin@...ux.intel.com>,
 "jolsa@...nel.org" <jolsa@...nel.org>,
 "irogers@...gle.com" <irogers@...gle.com>,
 "adrian.hunter@...el.com" <adrian.hunter@...el.com>,
 "tglx@...utronix.de" <tglx@...utronix.de>, "bp@...en8.de" <bp@...en8.de>,
 "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
 "x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
 "linux-perf-users@...r.kernel.org" <linux-perf-users@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf/x86: Fix open counting event error



On 2025-04-24 2:52 a.m., Ravi Bangoria wrote:
> On 23-Apr-25 12:17 PM, Luo Gengkun wrote:
>> Perf doesn't work at perf stat for hardware events:
>>
>>  $perf stat -- sleep 1
>>  Performance counter stats for 'sleep 1':
>>              16.44 msec task-clock                       #    0.016 CPUs utilized
>>                  2      context-switches                 #  121.691 /sec
>>                  0      cpu-migrations                   #    0.000 /sec
>>                 54      page-faults                      #    3.286 K/sec
>>    <not supported>	cycles
>>    <not supported>	instructions
>>    <not supported>	branches
>>    <not supported>	branch-misses
> 
> Wondering if it is worth to add this in perf test. Something like
> below?
> 
> --- a/tools/perf/tests/shell/stat.sh
> +++ b/tools/perf/tests/shell/stat.sh
> @@ -16,6 +16,24 @@ test_default_stat() {
>    echo "Basic stat command test [Success]"
>  }
>  
> +test_stat_count() {
> +  echo "stat count test"
> +
> +  if ! perf list | grep -q "cpu-cycles OR cycles"
> +  then
> +    echo "stat count test [Skipped cpu-cycles event missing]"
> +    return
> +  fi
> +
> +  if perf stat -e cycles true 2>&1 | grep -E -q "<not supported>"
> +  then
> +    echo "stat count test [Failed]"
> +    err=1
> +    return
> +  fi
> +  echo "stat count test [Success]"
> +}
> +
>  test_stat_record_report() {
>    echo "stat record and report test"
>    if ! perf stat record -o - true | perf stat report -i - 2>&1 | \
> @@ -201,6 +219,7 @@ test_hybrid() {
>  }
>  
>  test_default_stat
> +test_stat_count

I think the perf stat default should always be supported, not just cycles.
Maybe we should add the check in test_default_stat?

Thanks,
Kan>  test_stat_record_report
>  test_stat_record_script
>  test_stat_repeat_weak_groups
> ---
> 
> Thanks,
> Ravi
>