linux-kernel - Re: [PATCHSET v4 next 0/3] perf stat: add user_time and system

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Date:   Fri, 22 Apr 2022 16:52:00 -0700
From:   Namhyung Kim <namhyung@...il.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Florian Fischer <florian.fischer@...q.space>,
        linux-perf-users <linux-perf-users@...r.kernel.org>,
        Ian Rogers <irogers@...gle.com>,
        Xing Zhengjun <zhengjun.xing@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCHSET v4 next 0/3] perf stat: add user_time and system_time
 tool events

Hello,

On Fri, Apr 22, 2022 at 3:05 PM Arnaldo Carvalho de Melo
<acme@...nel.org> wrote:
>
> Em Wed, Apr 20, 2022 at 12:23:51PM +0200, Florian Fischer escreveu:
> > This patch series adds new internal events to perf stat exposing the times spend
> > in user and kernel mode in nanoseconds reported by rusage.
> >
> > During some benchmarking using perf it bothered me that I could not easily
> > retrieve those times from perf stat when using the machine readable output.
> >
> > But perf definitely knows about those values because in the human readable output
> > they are present.
> >
> > Therefore I exposed the times reported by rusage via the new tool events:
> > user_time and system_time.
> >
> > This allows to retrieved them in machine-readable output:
> >
> > $ ./perf stat -x, -e duration_time,user_time,system_time,cache-misses -- grep -q -r duration_time tools/perf
> > 72134524,ns,duration_time:u,72134524,100.00,,
> > 65225000,ns,user_time:u,65225000,100.00,,
> > 6865000,ns,ssystem_time:u,6865000,100.00,,

ssystem?  Looks like a typo.

Anyway it looks a little bit strange to me if we can get
system time in user mode only (the 'u' modifier).

Thanks,
Namhyung


> > 38705,,cache-misses:u,71189328,100.00,,
> >
> > The changes are mostly inspired by the code for the only other available
> > tool event: 'duration_time'.