From: Ingo Molnar <mingo@kernel.org>
To: Ian Rogers <irogers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>,
Adrian Hunter <adrian.hunter@intel.com>,
James Clark <james.clark@linaro.org>,
Chun-Tse Shao <ctshao@google.com>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1] perf stat display: Make %f precision consistent
Date: Tue, 9 Dec 2025 18:45:04 +0100 [thread overview]
Message-ID: <aThgIB2VQdAtEXKm@gmail.com> (raw)
In-Reply-To: <20251209173610.2033973-1-irogers@google.com>
* Ian Rogers <irogers@google.com> wrote:
> Commit bc22de9bcdb2 ("perf stat: Display time in precision based on
> std deviation") added multirun workload elapsed time. There was an
> effort to make the precision in the output most useful for the user,
> however, when gathering over runs it means the formatting varies. This
> change just makes the output format fixed.
>
> Before:
> ```
> $ while :; do perf stat --null --repeat 3 sleep 0.1 2>&1 | grep elapsed; done
> 0.101140 +- 0.000149 seconds time elapsed ( +- 0.15% )
> 0.1011396 +- 0.0000218 seconds time elapsed ( +- 0.02% )
> 0.101331 +- 0.000124 seconds time elapsed ( +- 0.12% )
> ^C
> $ while :; do perf stat --null --repeat 3 sleep 1 2>&1 | grep elapsed; done
> 1.001317 +- 0.000146 seconds time elapsed ( +- 0.01% )
> 1.001377 +- 0.000172 seconds time elapsed ( +- 0.02% )
> 1.00253 +- 0.00131 seconds time elapsed ( +- 0.13% )
> ```
>
> After:
> ```
> $ while :; do perf stat --null --repeat 3 sleep 0.1 2>&1 | grep elapsed; done
> 0.101406408 +- 0.000064778 seconds time elapsed ( +- 0.06% )
> 0.101367315 +- 0.000027253 seconds time elapsed ( +- 0.03% )
> 0.101434164 +- 0.000084750 seconds time elapsed ( +- 0.08% )
> ^C
> $ while :; do perf stat --null --repeat 3 sleep 1 2>&1 | grep elapsed; done
> 1.001525467 +- 0.000051703 seconds time elapsed ( +- 0.01% )
> 1.001375093 +- 0.000116200 seconds time elapsed ( +- 0.01% )
> 1.001141025 +- 0.000046361 seconds time elapsed ( +- 0.00% )
Perfect, thank you!
Tested-by: Ingo Molnar <mingo@kernel.org>
Ingo
prev parent reply other threads:[~2025-12-09 17:45 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-09 17:36 [PATCH v1] perf stat display: Make %f precision consistent Ian Rogers
2025-12-09 17:45 ` Ingo Molnar [this message]
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