linux-kernel - Re: [PATCH 4/8] perf test: Wait for a new thread when testing --per-thread record

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Message-ID: <CAP-5=fVehUL0YtVcn46nLNfpNr1UQ1dOvz2FixatQiDJkU3Ppw@mail.gmail.com>
Date:   Thu, 20 Oct 2022 16:57:23 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>, Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-perf-users@...r.kernel.org
Subject: Re: [PATCH 4/8] perf test: Wait for a new thread when testing
 --per-thread record

On Thu, Oct 20, 2022 at 10:26 AM Namhyung Kim <namhyung@...nel.org> wrote:
>
> Just running the target program is not enough to test multi-thread
> target because it'd be racy perf vs target startup.  I used the
> initial delay but it cannot guarantee for perf to see the thread.
>
> Instead, use wait_for_threads helper from shell/lib/waiting.sh to make
> sure it starts the sibling thread first.  Then perf record can use -p
> option to profile the target process.
>
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>

Acked-by: Ian Rogers <irogers@...gle.com>

Thanks,
Ian

> ---
>  tools/perf/tests/shell/record.sh | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
>
> diff --git a/tools/perf/tests/shell/record.sh b/tools/perf/tests/shell/record.sh
> index 952981481239..d1640d1daf2e 100755
> --- a/tools/perf/tests/shell/record.sh
> +++ b/tools/perf/tests/shell/record.sh
> @@ -4,6 +4,9 @@
>
>  set -e
>
> +shelldir=$(dirname "$0")
> +. "${shelldir}"/lib/waiting.sh
> +
>  err=0
>  perfdata=$(mktemp /tmp/__perf_test.perf.data.XXXXX)
>  testprog=$(mktemp /tmp/__perf_test.prog.XXXXXX)
> @@ -96,6 +99,30 @@ test_per_thread() {
>      err=1
>      return
>    fi
> +
> +  # run the test program in background (forever)
> +  ${testprog} 1 &
> +  TESTPID=$!
> +
> +  rm -f "${perfdata}"
> +
> +  wait_for_threads ${TESTPID} 2
> +  perf record -p "${TESTPID}" --per-thread -o "${perfdata}" sleep 1 2> /dev/null
> +  kill ${TESTPID}
> +
> +  if [ ! -e "${perfdata}" ]
> +  then
> +    echo "Per-thread record [Failed record -p]"
> +    err=1
> +    return
> +  fi
> +  if ! perf report -i "${perfdata}" -q | grep -q "${testsym}"
> +  then
> +    echo "Per-thread record [Failed -p missing output]"
> +    err=1
> +    return
> +  fi
> +
>    echo "Basic --per-thread mode test [Success]"
>  }
>
> --
> 2.38.0.135.g90850a2211-goog
>