linux-kernel - Re: [PATCH v1] perf test: AMD IBS swfilt skip kernel tests if paranoia is >1

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Message-ID: <aL9oL8aAMam676Ra@google.com>
Date: Mon, 8 Sep 2025 16:35:11 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Ravi Bangoria <ravi.bangoria@....com>,
	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>,
	Collin Funk <collin.funk1@...il.com>,
	James Clark <james.clark@...aro.org>,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] perf test: AMD IBS swfilt skip kernel tests if
 paranoia is >1

Hi Ian,

On Mon, Sep 08, 2025 at 03:17:27PM -0700, Ian Rogers wrote:
> If not root and the perf_event_paranoid is set >1 swfilt will fail to
> open the event failing the test. Add check to skip the test in that
> case.

Thanks for the fix!

> 
> Some corrections to the kernel/user sample count test.
> 
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
>  tools/perf/tests/shell/amd-ibs-swfilt.sh | 57 +++++++++++++++++-------
>  1 file changed, 41 insertions(+), 16 deletions(-)
> 
> diff --git a/tools/perf/tests/shell/amd-ibs-swfilt.sh b/tools/perf/tests/shell/amd-ibs-swfilt.sh
> index 7045ec72ba4c..80d5bf8db40c 100755
> --- a/tools/perf/tests/shell/amd-ibs-swfilt.sh
> +++ b/tools/perf/tests/shell/amd-ibs-swfilt.sh
> @@ -1,6 +1,10 @@
>  #!/bin/bash
>  # AMD IBS software filtering
>  
> +ParanoidAndNotRoot() {
> +  [ "$(id -u)" != 0 ] && [ "$(cat /proc/sys/kernel/perf_event_paranoid)" -gt $1 ]
> +}
> +
>  echo "check availability of IBS swfilt"
>  
>  # check if IBS PMU is available
> @@ -16,6 +20,7 @@ if [ ! -f /sys/bus/event_source/devices/ibs_op/format/swfilt ]; then
>  fi
>  
>  echo "run perf record with modifier and swfilt"
> +err=0
>  
>  # setting any modifiers should fail
>  perf record -B -e ibs_op//u -o /dev/null true 2> /dev/null
> @@ -31,11 +36,17 @@ if [ $? -ne 0 ]; then
>      exit 1
>  fi
>  
> -# setting it with swfilt=1 should be fine
> -perf record -B -e ibs_op/swfilt=1/k -o /dev/null true
> -if [ $? -ne 0 ]; then
> -    echo "[FAIL] IBS op PMU cannot handle swfilt for exclude_user"
> -    exit 1
> +if ! ParanoidAndNotRoot 1
> +then
> +    # setting it with swfilt=1 should be fine
> +    perf record -B -e ibs_op/swfilt=1/k -o /dev/null true
> +    if [ $? -ne 0 ]; then
> +        echo "[FAIL] IBS op PMU cannot handle swfilt for exclude_user"
> +        exit 1
> +    fi
> +else
> +    echo "[SKIP] not root and perf_event_paranoid too high for exclude_user"
> +    err=2
>  fi
>  
>  # check ibs_fetch PMU as well
> @@ -46,22 +57,36 @@ if [ $? -ne 0 ]; then
>  fi
>  
>  # check system wide recording
> -perf record -aB --synth=no -e ibs_op/swfilt/k -o /dev/null true
> -if [ $? -ne 0 ]; then
> -    echo "[FAIL] IBS op PMU cannot handle swfilt in system-wide mode"
> -    exit 1
> +if ! ParanoidAndNotRoot 1
> +then
> +    perf record -aB --synth=no -e ibs_op/swfilt/k -o /dev/null true
> +    if [ $? -ne 0 ]; then
> +        echo "[FAIL] IBS op PMU cannot handle swfilt in system-wide mode"
> +        exit 1
> +    fi
> +else
> +    echo "[SKIP] not root and perf_event_paranoid too high for exclude_user"
> +    err=2
>  fi
>  
>  echo "check number of samples with swfilt"
>  
> -kernel_sample=$(perf record -e ibs_op/swfilt/u -o- true | perf script -i- -F misc | grep -c ^K)
> -if [ ${kernel_sample} -ne 0 ]; then
> -    echo "[FAIL] unexpected kernel samples: " ${kernel_sample}
> -    exit 1
> -fi
> -
> -user_sample=$(perf record -e ibs_fetch/swfilt/k -o- true | perf script -i- -F misc | grep -c ^U)
> +user_sample=$(perf record -e ibs_op/swfilt/u -o- true | perf script -i- -F misc | grep -c ^U)

I think it should count kernel samples now (with ^K) as it sets 'u'
modifier (exclude_kernel).


>  if [ ${user_sample} -ne 0 ]; then
>      echo "[FAIL] unexpected user samples: " ${user_sample}

So that it should not have unexpected kernel samples.


>      exit 1
>  fi
> +
> +if ! ParanoidAndNotRoot 1
> +then
> +    kernel_sample=$(perf record -e ibs_fetch/swfilt/k -o- true | perf script -i- -F misc | grep -c ^K)
> +    if [ ${kernel_sample} -ne 0 ]; then
> +        echo "[FAIL] unexpected kernel samples: " ${kernel_sample}

Vice versa.  It should count unexpected user samples from 'k' modifier.

Thanks,
Namhyung


> +        exit 1
> +    fi
> +else
> +    echo "[SKIP] not root and perf_event_paranoid too high for exclude_user"
> +    err=2
> +fi
> +
> +exit $err
> -- 
> 2.51.0.384.g4c02a37b29-goog
>