Re: [Patch v3] perf tests: Add auto counter reload (ACR) sampling test

[Falcon, Thomas]

On Tue, 2026-04-21 at 12:55 +0800, Dapeng Mi wrote:
> 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.
> 
> Additionally, enhance ratio_to_prev test to verify ACR sampling as
> well
> if ACR is supported.
> 
> Signed-off-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
> ---
> 
> V3: Move ratio-to-prev ACR sampling test into ratio_to_prev test.
> V2:
> https://lore.kernel.org/all/20260420025501.2133495-1-dapeng1.mi@xxxxxxxxxxxxxxx/
> v1:
> https://lore.kernel.org/all/20260413010920.546501-1-dapeng1.mi@xxxxxxxxxxxxxxx/
> 
>  tools/perf/tests/shell/record.sh | 92
> +++++++++++++++++++++++++++++++-
>  1 file changed, 91 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/tests/shell/record.sh
> b/tools/perf/tests/shell/record.sh
> index 7cb81cf3444a..091d8b0a998b 100755
> --- a/tools/perf/tests/shell/record.sh
> +++ b/tools/perf/tests/shell/record.sh
> @@ -402,7 +402,52 @@ 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}"
> +  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]"
> +    echo "Auto counter reload sampling [Success]"

Should this "Success" message be here?

Thanks,
Tom

> +    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
> +  echo "Auto counter reload sampling [Success]"
> +}
> +
>  test_ratio_to_prev() {
> +  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 "ratio-to-prev test"
>    if ! perf record -o /dev/null -e "{instructions,
> cycles/period=100000,ratio-to-prev=0.5/}" \
>       true 2> /dev/null
> @@ -438,7 +483,51 @@ test_ratio_to_prev() {
>      err=1
>      return
>    fi
> -  echo "Basic ratio-to-prev record test [Success]"
> +
> +  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 ${cpu} ratio-to-prev sampling
> [Failed sampling]"
> +      ratio_err=1
> +      return
> +    fi
> +    if ! perf script -i "${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 "$ratio_err" -eq 0
> +  then
> +    echo "Basic ratio-to-prev record test [Success]"
> +  else
> +    err="${ratio_err}"
> +  fi
>  }
>  
>  # raise the limit of file descriptors to minimum
> @@ -457,6 +546,7 @@ test_leader_sampling
>  test_topdown_leader_sampling
>  test_precise_max
>  test_callgraph
> +test_acr_sampling
>  test_ratio_to_prev
>  
>  # restore the default value