Re: [PATCH] perf: test: Speed up running brstack test

[Arnaldo Carvalho de Melo]

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@xxxxxxxxxx> wrote:
> >
> > From: James Clark <james.clark@xxxxxxx>
> >
> > 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@xxxxxxx>
> > Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
> > [robh: Drop changing loop iterations on arm64. Squash blank line fix and redo commit msg]
> > Signed-off-by: Rob Herring (Arm) <robh@xxxxxxxxxx>
> > ---
> > 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@xxxxxxx/
> >
> >  tools/perf/tests/shell/test_brstack.sh | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> Ping!

Thanks, applied.

- Arnaldo