linux-kernel - Re: [PATCH v2] perf test stat: Avoid hybrid assumption when virtualized

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Message-ID: <56bbbfea-ec52-4f2e-a402-57bf59103416@linaro.org>
Date: Fri, 13 Dec 2024 08:55:54 +0000
From: James Clark <james.clark@...aro.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
 Arnaldo Carvalho de Melo <acme@...nel.org>,
 Namhyung Kim <namhyung@...nel.org>, Mark Rutland <mark.rutland@....com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Jiri Olsa <jolsa@...nel.org>, Adrian Hunter <adrian.hunter@...el.com>,
 Kan Liang <kan.liang@...ux.intel.com>, linux-perf-users@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] perf test stat: Avoid hybrid assumption when
 virtualized



On 12/12/2024 5:33 pm, Ian Rogers wrote:
> The cycles event will fallback to task-clock in the hybrid test when
> running virtualized. Change the test to not fail for this.
> 
> Fixes: a6b8bb2addd0 ("perf test: Add a test for default perf stat command")
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
>   tools/perf/tests/shell/stat.sh | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/tests/shell/stat.sh b/tools/perf/tests/shell/stat.sh
> index 5a2ca2bcf94d..da42427bb077 100755
> --- a/tools/perf/tests/shell/stat.sh
> +++ b/tools/perf/tests/shell/stat.sh
> @@ -163,7 +163,11 @@ test_hybrid() {
>     # Run default Perf stat
>     cycles_events=$(perf stat -- true 2>&1 | grep -E "/cycles/|  cycles  " | wc -l)
>   
> -  if [ "$pmus" -ne "$cycles_events" ]
> +  # The expectation is that default output will have a cycles events on each
> +  # hybrid PMU. In situations with no cycles PMU events, like virtualized, this
> +  # can fall back to task-clock and so the end count may be 0. Fail if neither
> +  # condition holds.
> +  if [ "$pmus" -ne "$cycles_events" ] && [ "0" -ne "$cycles_events" ]
>     then
>       echo "hybrid test [Found $pmus PMUs but $cycles_events cycles events. Failed]"
>       err=1

Reviewed-by: James Clark <james.clark@...aro.org>