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

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Message-ID: <CAL_JsqJqJzAvG1wVG2y_FBApVxF8wapP+7+xGXeZ2kHiCqy-jQ@mail.gmail.com>
Date: Mon, 13 Jan 2025 08:25:45 -0600
From: Rob Herring <robh@...nel.org>
To: 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>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	"Liang, Kan" <kan.liang@...ux.intel.com>
Cc: 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 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!

>
> diff --git a/tools/perf/tests/shell/test_brstack.sh b/tools/perf/tests/shell/test_brstack.sh
> index 5f14d0cb013f..e01df7581393 100755
> --- a/tools/perf/tests/shell/test_brstack.sh
> +++ b/tools/perf/tests/shell/test_brstack.sh
> @@ -30,7 +30,7 @@ test_user_branches() {
>         echo "Testing user branch stack sampling"
>
>         perf record -o $TMPDIR/perf.data --branch-filter any,save_type,u -- ${TESTPROG} > /dev/null 2>&1
> -       perf script -i $TMPDIR/perf.data --fields brstacksym | xargs -n1 > $TMPDIR/perf.script
> +       perf script -i $TMPDIR/perf.data --fields brstacksym | tr -s ' ' '\n' > $TMPDIR/perf.script
>
>         # example of branch entries:
>         #       brstack_foo+0x14/brstack_bar+0x40/P/-/-/0/CALL
> @@ -59,7 +59,7 @@ test_filter() {
>         echo "Testing branch stack filtering permutation ($test_filter_filter,$test_filter_expect)"
>
>         perf record -o $TMPDIR/perf.data --branch-filter $test_filter_filter,save_type,u -- ${TESTPROG} > /dev/null 2>&1
> -       perf script -i $TMPDIR/perf.data --fields brstack | xargs -n1 > $TMPDIR/perf.script
> +       perf script -i $TMPDIR/perf.data --fields brstack | tr -s ' ' '\n' | grep '.' > $TMPDIR/perf.script
>
>         # fail if we find any branch type that doesn't match any of the expected ones
>         # also consider UNKNOWN branch types (-)
> --
> 2.45.2
>