linux-kernel - Re: [PATCH v2 2/2] perf test: Add sched latency and script shell tests

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Message-ID: <aFW5aknT69UR3CTV@google.com>
Date: Fri, 20 Jun 2025 12:41:30 -0700
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>,
	Mark Rutland <mark.rutland@....com>,
	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>, linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v2 2/2] perf test: Add sched latency and script shell
 tests

On Wed, Jun 18, 2025 at 05:20:34PM -0700, Ian Rogers wrote:
> Add shell tests covering the `perf sched latency` and `perf sched
> script` commands. The test creates 2 noploop processes on the same
> forced CPU, it then checks that the process appears in the `perf
> sched` output.
> 
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
> v2: Skip the test if not root due to permissions.
> ---
>  tools/perf/tests/shell/sched.sh | 91 +++++++++++++++++++++++++++++++++
>  1 file changed, 91 insertions(+)
>  create mode 100755 tools/perf/tests/shell/sched.sh
> 
> diff --git a/tools/perf/tests/shell/sched.sh b/tools/perf/tests/shell/sched.sh
> new file mode 100755
> index 000000000000..0a4fe3f414e1
> --- /dev/null
> +++ b/tools/perf/tests/shell/sched.sh
> @@ -0,0 +1,91 @@
> +#!/bin/bash
> +# perf sched tests
> +# SPDX-License-Identifier: GPL-2.0
> +
> +set -e
> +
> +if [ "$(id -u)" != 0 ]; then
> +  echo "[Skip] No root permission"
> +  exit 2
> +fi
> +
> +err=0
> +perfdata=$(mktemp /tmp/__perf_test_sched.perf.data.XXXXX)
> +PID1=0
> +PID2=0
> +
> +cleanup() {
> +  rm -f "${perfdata}"
> +  rm -f "${perfdata}".old
> +
> +  trap - EXIT TERM INT
> +}
> +
> +trap_cleanup() {
> +  echo "Unexpected signal in ${FUNCNAME[1]}"
> +  cleanup
> +  exit 1
> +}
> +trap trap_cleanup EXIT TERM INT
> +
> +start_noploops() {
> +  # Start two noploop workloads on CPU0 to trigger scheduling.
> +  taskset -c 0 perf test -w noploop 10 &
> +  PID1=$!
> +  taskset -c 0 perf test -w noploop 10 &
> +  PID2=$!

You can use 'thloop' workload which runs 2 threads at the same time.
Then you don't need to handle the background processes and run it
directly with perf test.

Thanks,
Namhyung

> +
> +  if ! grep -q 'Cpus_allowed_list:\s*0$' "/proc/$PID1/status"
> +  then
> +    echo "Sched [Error taskset did not work for the 1st noploop ($PID1)]"
> +    grep Cpus_allowed /proc/$PID1/status
> +    err=1
> +  fi
> +
> +  if ! grep -q 'Cpus_allowed_list:\s*0$' "/proc/$PID2/status"
> +  then
> +    echo "Sched [Error taskset did not work for the 2nd noploop ($PID2)]"
> +    grep Cpus_allowed /proc/$PID2/status
> +    err=1
> +  fi
> +}
> +
> +cleanup_noploops() {
> +  kill "$PID1" "$PID2"
> +}
> +
> +test_sched_latency() {
> +  echo "Sched latency"
> +
> +  start_noploops
> +
> +  perf sched record --no-inherit -o "${perfdata}" sleep 1
> +  if ! perf sched latency -i "${perfdata}" | grep -q perf-noploop
> +  then
> +    echo "Sched latency [Failed missing output]"
> +    err=1
> +  fi
> +
> +  cleanup_noploops
> +}
> +
> +test_sched_script() {
> +  echo "Sched script"
> +
> +  start_noploops
> +
> +  perf sched record --no-inherit -o "${perfdata}" sleep 1
> +  if ! perf sched script -i "${perfdata}" | grep -q perf-noploop
> +  then
> +    echo "Sched script [Failed missing output]"
> +    err=1
> +  fi
> +
> +  cleanup_noploops
> +}
> +
> +test_sched_latency
> +test_sched_script
> +
> +cleanup
> +exit $err
> -- 
> 2.50.0.rc2.701.gf1e915cc24-goog
>