linux-kernel - Re: [PATCH 2/2] perf stat: fix unexpected delay behaviour

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Date:   Wed, 14 Dec 2022 14:26:44 +0000
From:   James Clark <james.clark@....com>
To:     Namhyung Kim <namhyung@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Adrián Herrera Arcila <adrian.herrera@....com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        leo.yan@...aro.org, songliubraving@...com, peterz@...radead.org,
        mingo@...hat.com, mark.rutland@....com,
        alexander.shishkin@...ux.intel.com, jolsa@...nel.org
Subject: Re: [PATCH 2/2] perf stat: fix unexpected delay behaviour



On 13/12/2022 16:40, Namhyung Kim wrote:
> Hi,
> 
> On Tue, Dec 13, 2022 at 6:44 AM Arnaldo Carvalho de Melo
> <acme@...nel.org> wrote:
>>
>> Em Mon, Aug 01, 2022 at 09:20:37AM +0100, James Clark escreveu:
>>>
>>>
>>> On 29/07/2022 17:12, Adrián Herrera Arcila wrote:
>>>> The described --delay behaviour is to delay the enablement of events, but
>>>> not the execution of the command, if one is passed, which is incorrectly
>>>> the current behaviour.
>>>>
>>>> This patch decouples the enablement from the delay, and enables events
>>>> before or after launching the workload dependent on the options passed
>>>> by the user. This code structure is inspired by that in perf-record, and
>>>> tries to be consistent with it.
>>>>
>>>> Link: https://lore.kernel.org/linux-perf-users/7BFD066E-B0A8-49D4-B635-379328F0CF4C@fb.com
>>>> Fixes: d0a0a511493d ("perf stat: Fix forked applications enablement of counters")
>>>> Signed-off-by: Adrián Herrera Arcila <adrian.herrera@....com>
>>>> ---
>>>>  tools/perf/builtin-stat.c | 56 ++++++++++++++++++++++-----------------
>>>>  1 file changed, 32 insertions(+), 24 deletions(-)
>>>
>>> Looks good to me. Fixes the counter delay issue and the code is pretty
>>> similar to perf record now. Although I would wait for Leo's or Song's
>>> comment as well because they were involved.
>>
>> I think I didn't notice Leo's ack, it still applies, so I'm doing it
>> now.
> 
> I think the BPF counters should be enabled/disabled together.

I did notice that difference between the two, but I wasn't sure of the
exact reason that it was done that way on Adrián's version. It seems
like it's not separated in perf record so maybe you are right.

> 
> Thanks,
> Namhyung