Re: [PATCH v1] perf stat display: Make %f precision consistent
From: Arnaldo Carvalho de Melo
Date: Mon Jan 12 2026 - 13:56:22 EST
On Thu, Jan 08, 2026 at 11:25:17AM -0800, Ian Rogers wrote:
> On Tue, Dec 9, 2025 at 9:45 AM Ingo Molnar <mingo@xxxxxxxxxx> wrote:
> >
> > * Ian Rogers <irogers@xxxxxxxxxx> 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@xxxxxxxxxx>
>
> Ping.
Thanks, applied to perf-tools-next,
- Arnaldo