linux-kernel - Re: [PATCH] perf: test: Speed up running brstack test

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Message-ID: <Z4UqbCJu-kgOB59w@x1>
Date: Mon, 13 Jan 2025 11:59:56 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Rob Herring <robh@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	James Clark <james.clark@...aro.org>,
	Anshuman Khandual <anshuman.khandual@....com>,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf: test: Speed up running brstack test

On Mon, Jan 13, 2025 at 08:25:45AM -0600, Rob Herring wrote:
> On Fri, Dec 13, 2024 at 5:19 PM Rob Herring (Arm) <robh@...nel.org> wrote:
> >
> > From: James Clark <james.clark@....com>
> >
> > The brstack test runs quite slowly in software models. Part of the reason
> > is "xargs -n1" is quite inefficient in replacing spaces with newlines.
> > While that's not noticeable on normal machines, it is on software models.
> > Use "tr -s ' ' '\n'" instead which can do the same transformation, but is
> > much faster. For comparison on an M1 Macbook Pro:
> >
> > $ time seq -s ' ' 10000 | xargs -n1 > /dev/null
> >
> > real    0m2.729s
> > user    0m2.009s
> > sys     0m0.914s
> > $ time seq -s ' ' 10000 | tr -s ' ' '\n' | grep '.' > /dev/null
> >
> > real    0m0.002s
> > user    0m0.001s
> > sys     0m0.001s
> >
> > The "grep '.'" is also needed to remove any remaining blank lines.
> >
> > Signed-off-by: James Clark <james.clark@....com>
> > Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> > [robh: Drop changing loop iterations on arm64. Squash blank line fix and redo commit msg]
> > Signed-off-by: Rob Herring (Arm) <robh@...nel.org>
> > ---
> > Originally part of this series[1], but I've dropped any Arm specifics,
> > and it stands on its own. No reason this needs to wait on Arm BRBE
> > support (which I'm working on now). I don't expect to have other changes
> > to this test related to BRBE anymore.
> >
> > [1] https://lore.kernel.org/all/20240613061731.3109448-8-anshuman.khandual@arm.com/
> >
> >  tools/perf/tests/shell/test_brstack.sh | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> Ping!

Thanks, applied.

- Arnaldo