[Patch v2] perf tests: Add auto counter reload (ACR) sampling test

[Patch v2] perf tests: Add auto counter reload (ACR) sampling test

[Dapeng Mi]

Add auto counter reload sampling test to verify that the intended event
records can be captured and the self-reloaded events won't generate any
records.

Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
---

V2: 1) add ratio_to_prev option test. 2) Adjust sampling period to
better match the "perf test -w thloop" workload
v1: https://lore.kernel.org/all/20260413010920.546501-1-dapeng1.mi@linux.intel.com/

 tools/perf/tests/shell/record.sh | 89 ++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)

diff --git a/tools/perf/tests/shell/record.sh b/tools/perf/tests/shell/record.sh
index 7cb81cf3444a..a05b0c8b6d6b 100755
--- a/tools/perf/tests/shell/record.sh
+++ b/tools/perf/tests/shell/record.sh
@@ -402,6 +402,94 @@ test_callgraph() {
   echo "Callgraph test [Success]"
 }
 
+test_acr_sampling() {
+  events="{instructions/period=40000,acr_mask=0x2/u,cycles/period=20000,acr_mask=0x3/u}"
+  pebs_events="{instructions/period=40000,acr_mask=0x2/pu,cycles/period=20000,acr_mask=0x3/u}"
+  ratio_events="{instructions:u,cycles/period=20000,ratio-to-prev=0.5/u}"
+  p_core_ratio_events="{cpu_core/instructions/u,cpu_core/cycles,period=20000,ratio-to-prev=0.5/u}"
+  e_core_ratio_events="{cpu_atom/instructions/u,cpu_atom/cycles,period=20000,ratio-to-prev=0.5/u}"
+  echo "Auto counter reload (ACR) sampling test"
+  if ! perf record -o "${perfdata}" -e "${events}" ${testprog} 2> /dev/null
+  then
+    echo "Auto counter reload sampling [Skipped not supported]"
+    return
+  fi
+  if ! perf script -i "${perfdata}" -F event | grep -q "instructions"
+  then
+    echo "Auto counter reload sampling [Failed missing instructions event]"
+    err=1
+    return
+  fi
+  if perf script -i "${perfdata}" -F event | grep -q "cycles"
+  then
+    echo "Auto counter reload sampling [Failed cycles event shouldn't be sampled]"
+    err=1
+    return
+  fi
+  if ! perf record -o "${perfdata}" -e "${pebs_events}" ${testprog} 2> /dev/null
+  then
+    echo "Auto counter reload PEBS sampling [Skipped not supported]"
+    return
+  fi
+  if ! perf script -i "${perfdata}" -F event | grep -q "instructions"
+  then
+    echo "Auto counter reload PEBS sampling [Failed missing instructions event]"
+    err=1
+    return
+  fi
+  if perf script -i "${perfdata}" -F event | grep -q "cycles"
+  then
+    echo "Auto counter reload PEBS sampling [Failed cycles event shouldn't be sampled]"
+    err=1
+    return
+  fi
+
+  ratio_err=0
+  do_ratio_to_prev_test() {
+    local events=$1
+    local cpu=$2
+    if ! perf record -o "${perfdata}" -e "${events}" ${testprog} 2> /dev/null
+    then
+      echo "Auto counter reload ${cpu} ratio-to-prev sampling [Failed not supported]"
+      ratio_err=1
+      return
+    fi
+    if ! perf script -i "${perfdata}" -F event | grep -q "instructions"
+    then
+      echo "Auto counter reload ${cpu} ratio-to-prev sampling [Failed missing instructions event]"
+      ratio_err=1
+      return
+    fi
+    if perf script -i "${perfdata}" -F event | grep -q "cycles"
+    then
+      echo "Auto counter reload ${cpu} ratio-to-prev sampling [Failed cycles event shouldn't be sampled]"
+      ratio_err=1
+      return
+    fi
+  }
+
+  # ratio-to-prev sampling would fallback to normal sampling if ACR sampling
+  # is not supported, so acr_mask must be checked before testing ratio-to-prev sampling.
+  if [ -e /sys/bus/event_source/devices/cpu/format/acr_mask ]
+  then
+    do_ratio_to_prev_test "${ratio_events}" ""
+  fi
+  if [ -e /sys/bus/event_source/devices/cpu_core/format/acr_mask ]
+  then
+    do_ratio_to_prev_test "${p_core_ratio_events}" "P-core"
+  fi
+  if [ -e /sys/bus/event_source/devices/cpu_atom/format/acr_mask ]
+  then
+    do_ratio_to_prev_test "${e_core_ratio_events}" "E-core"
+  fi
+  if test "$ratio_err" -eq 0
+  then
+    echo "Auto counter reload sampling [Success]"
+  else
+    err="${ratio_err}"
+  fi
+}
+
 test_ratio_to_prev() {
   echo "ratio-to-prev test"
   if ! perf record -o /dev/null -e "{instructions, cycles/period=100000,ratio-to-prev=0.5/}" \
@@ -458,6 +546,7 @@ test_topdown_leader_sampling
 test_precise_max
 test_callgraph
 test_ratio_to_prev
+test_acr_sampling
 
 # restore the default value
 ulimit -Sn $default_fd_limit
-- 
2.34.1

Re: [Patch v2] perf tests: Add auto counter reload (ACR) sampling test

[sashiko-bot]

Sashiko AI review found 1 potential issue(s):
- [Medium] Early return in the PEBS support check unintentionally skips subsequent ratio-to-prev tests and the final success message.
--

commit 4863d01ec678cdb7aeb26a69a3ff812dd0a8e16c
Author: Dapeng Mi <dapeng1.mi@linux.intel.com>

perf tests: Add auto counter reload (ACR) sampling test

This commit adds an auto counter reload sampling test to verify that the
intended event records can be captured and that self-reloaded events
won't generate any records.

> diff --git a/tools/perf/tests/shell/record.sh b/tools/perf/tests/shell/record.sh
> index 7cb81cf3444a7..a05b0c8b6d6b6 100755
> --- a/tools/perf/tests/shell/record.sh
> +++ b/tools/perf/tests/shell/record.sh
> @@ -402,6 +402,94 @@ test_callgraph() {

[ ... ]

> +  if ! perf record -o "${perfdata}" -e "${pebs_events}" ${testprog} 2> /dev/null
> +  then
> +    echo "Auto counter reload PEBS sampling [Skipped not supported]"
> +    return
> +  fi

If PEBS is not supported, this early return exits the entire function. Does
this unintentionally skip the subsequent ratio-to-prev tests and prevent the
script from printing the final "Auto counter reload sampling [Success]"
message?

The ratio-to-prev tests use the u modifier rather than the p modifier, so it
appears they should be allowed to run even if PEBS is not supported.

> +  if ! perf script -i "${perfdata}" -F event | grep -q "instructions"
> +  then
> +    echo "Auto counter reload PEBS sampling [Failed missing instructions event]"
> +    err=1
> +    return
> +  fi

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260420025501.2133495-1-dapeng1.mi@linux.intel.com?part=1

Re: [Patch v2] perf tests: Add auto counter reload (ACR) sampling test

[Mi, Dapeng]

On 4/20/2026 11:10 AM, sashiko-bot@kernel.org wrote:
> Sashiko AI review found 1 potential issue(s):
> - [Medium] Early return in the PEBS support check unintentionally skips subsequent ratio-to-prev tests and the final success message.
> --
>
> commit 4863d01ec678cdb7aeb26a69a3ff812dd0a8e16c
> Author: Dapeng Mi <dapeng1.mi@linux.intel.com>
>
> perf tests: Add auto counter reload (ACR) sampling test
>
> This commit adds an auto counter reload sampling test to verify that the
> intended event records can be captured and that self-reloaded events
> won't generate any records.
>
>> diff --git a/tools/perf/tests/shell/record.sh b/tools/perf/tests/shell/record.sh
>> index 7cb81cf3444a7..a05b0c8b6d6b6 100755
>> --- a/tools/perf/tests/shell/record.sh
>> +++ b/tools/perf/tests/shell/record.sh
>> @@ -402,6 +402,94 @@ test_callgraph() {
> [ ... ]
>
>> +  if ! perf record -o "${perfdata}" -e "${pebs_events}" ${testprog} 2> /dev/null
>> +  then
>> +    echo "Auto counter reload PEBS sampling [Skipped not supported]"
>> +    return
>> +  fi
> If PEBS is not supported, this early return exits the entire function. Does
> this unintentionally skip the subsequent ratio-to-prev tests and prevent the
> script from printing the final "Auto counter reload sampling [Success]"
> message?
>
> The ratio-to-prev tests use the u modifier rather than the p modifier, so it
> appears they should be allowed to run even if PEBS is not supported.

Hmm, maybe It's a better choice to integrate the ratio_prev_test sampling
test into the test_ratio_to_prev case. Thanks.


>
>> +  if ! perf script -i "${perfdata}" -F event | grep -q "instructions"
>> +  then
>> +    echo "Auto counter reload PEBS sampling [Failed missing instructions event]"
>> +    err=1
>> +    return
>> +  fi