linux-kernel - Re: [PATCH v1 2/2] perf test: Add test that command line period overrides sysfs/json values

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Message-ID: <aQw3GqjU4GRLfjIF@google.com>
Date: Wed, 5 Nov 2025 21:50:18 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	James Clark <james.clark@...aro.org>, linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v1 2/2] perf test: Add test that command line period
 overrides sysfs/json values

On Mon, Nov 03, 2025 at 09:22:00PM -0800, Ian Rogers wrote:
> On Mon, Nov 3, 2025 at 7:37 PM Namhyung Kim <namhyung@...nel.org> wrote:
> >
> > On Wed, Oct 29, 2025 at 03:26:38PM -0700, Ian Rogers wrote:
> > > The behavior of weak terms is subtle, add a test that they aren't
> > > accidentally broken.
> > >
> > > Signed-off-by: Ian Rogers <irogers@...gle.com>
> > > ---
> > >  tools/perf/tests/shell/record_weak_term.sh | 25 ++++++++++++++++++++++
> > >  1 file changed, 25 insertions(+)
> > >  create mode 100755 tools/perf/tests/shell/record_weak_term.sh
> > >
> > > diff --git a/tools/perf/tests/shell/record_weak_term.sh b/tools/perf/tests/shell/record_weak_term.sh
> > > new file mode 100755
> > > index 000000000000..7b747b383796
> > > --- /dev/null
> > > +++ b/tools/perf/tests/shell/record_weak_term.sh
> > > @@ -0,0 +1,25 @@
> > > +#!/bin/bash
> > > +# record weak terms
> > > +# SPDX-License-Identifier: GPL-2.0
> > > +# Test that command line options override weak terms from sysfs or inbuilt json.
> > > +set -e
> > > +
> > > +shelldir=$(dirname "$0")
> > > +# shellcheck source=lib/setup_python.sh
> > > +. "${shelldir}"/lib/setup_python.sh
> > > +
> > > +
> > > +event=$(perf list --json | $PYTHON -c "import json,sys; next((print(e['EventName']) for e in json.load(sys.stdin) if e.get('Encoding') and 'period=' in e.get('Encoding')))")
> >
> > This line is too long
> 
> Is there a good way to split such a line?

Wouldn't this work?

  event=$(perf list --json | python -c '
  import sys, json
  for e in json.load(sys.stdin):
    if e.get("Encoding") and "period=" in e.get("Encoding"):
      print(e["EventName"])')

> 
> > and needs some explanation like what's like the original text and what it does.
> 
> I thought that was covered in the "if" below:

Yeah, but I think it's useful to have an example JSON text.

Thanks,
Namhyung

> 
> > > +if [[ "$?" != "0" ]]
> > > +then
> > > +  echo "No sysfs/json events with inbuilt period."
> > > +  exit 2
> > > +fi
> 
> Thanks,
> Ian
> 
> > > +
> > > +if ! perf record -c 1000 -vv -e "$event" -o /dev/null true 2>&1 | \
> > > +  grep -q -F '{ sample_period, sample_freq }   1000'
> > > +then
> > > +  echo "Unexpected verbose output and sample period"
> > > +  exit 1
> > > +fi
> > > +exit 0
> > > --
> > > 2.51.1.851.g4ebd6896fd-goog
> > >