linux-kernel - Re: [PATCH v1 1/4] perf test shell lbr: Avoid failures with perf event paranoia

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Message-ID: <aMmztG_F1KuAKKq9@x1>
Date: Tue, 16 Sep 2025 16:00:04 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Ian Rogers <irogers@...gle.com>
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>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Chun-Tse Shao <ctshao@...gle.com>,
	James Clark <james.clark@...aro.org>,
	Howard Chu <howardchu95@...il.com>, linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v1 1/4] perf test shell lbr: Avoid failures with perf
 event paranoia

On Thu, Aug 21, 2025 at 03:18:31PM -0700, Ian Rogers wrote:
> When not running as root and with higher perf event paranoia values
> the perf record LBR tests could fail rather than skipping the
> problematic tests. Add the sensitivity to the test and confirm it
> passes with paranoia values from -1 to 2.

Thanks, applied to perf-tools-next,

Committer testing:

Testing with '$ perf test -vv lbr', i.e. as non root, and then comparing
the output shows the mentioned errors before this patch:

  acme@x1:~$ grep -m1 "model name" /proc/cpuinfo
  model name    : 13th Gen Intel(R) Core(TM) i7-1365U
  acme@x1:~$ 

Before:

 132: perf record LBR tests            : Skip

After:

 132: perf record LBR tests            : Ok

- Arnaldo
 
> Fixes: 32559b99e0f5 ("perf test: Add set of perf record LBR tests")
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
>  tools/perf/tests/shell/record_lbr.sh | 26 ++++++++++++++++++++------
>  1 file changed, 20 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/perf/tests/shell/record_lbr.sh b/tools/perf/tests/shell/record_lbr.sh
> index 6fcb5e52b9b4..78a02e90ece1 100755
> --- a/tools/perf/tests/shell/record_lbr.sh
> +++ b/tools/perf/tests/shell/record_lbr.sh
> @@ -4,6 +4,10 @@
>  
>  set -e
>  
> +ParanoidAndNotRoot() {
> +  [ "$(id -u)" != 0 ] && [ "$(cat /proc/sys/kernel/perf_event_paranoid)" -gt $1 ]
> +}
> +
>  if [ ! -f /sys/bus/event_source/devices/cpu/caps/branches ] &&
>     [ ! -f /sys/bus/event_source/devices/cpu_core/caps/branches ]
>  then
> @@ -23,6 +27,7 @@ cleanup() {
>  }
>  
>  trap_cleanup() {
> +  echo "Unexpected signal in ${FUNCNAME[1]}"
>    cleanup
>    exit 1
>  }
> @@ -123,8 +128,11 @@ lbr_test "-j ind_call" "any indirect call" 2
>  lbr_test "-j ind_jmp" "any indirect jump" 100
>  lbr_test "-j call" "direct calls" 2
>  lbr_test "-j ind_call,u" "any indirect user call" 100
> -lbr_test "-a -b" "system wide any branch" 2
> -lbr_test "-a -j any_call" "system wide any call" 2
> +if ! ParanoidAndNotRoot 1
> +then
> +  lbr_test "-a -b" "system wide any branch" 2
> +  lbr_test "-a -j any_call" "system wide any call" 2
> +fi
>  
>  # Parallel
>  parallel_lbr_test "-b" "parallel any branch" 100 &
> @@ -141,10 +149,16 @@ parallel_lbr_test "-j call" "parallel direct calls" 100 &
>  pid6=$!
>  parallel_lbr_test "-j ind_call,u" "parallel any indirect user call" 100 &
>  pid7=$!
> -parallel_lbr_test "-a -b" "parallel system wide any branch" 100 &
> -pid8=$!
> -parallel_lbr_test "-a -j any_call" "parallel system wide any call" 100 &
> -pid9=$!
> +if ParanoidAndNotRoot 1
> +then
> +  pid8=
> +  pid9=
> +else
> +  parallel_lbr_test "-a -b" "parallel system wide any branch" 100 &
> +  pid8=$!
> +  parallel_lbr_test "-a -j any_call" "parallel system wide any call" 100 &
> +  pid9=$!
> +fi
>  
>  for pid in $pid1 $pid2 $pid3 $pid4 $pid5 $pid6 $pid7 $pid8 $pid9
>  do
> -- 
> 2.51.0.rc2.233.g662b1ed5c5-goog