Commit 1c5721ca authored by Chun-Tse Shao's avatar Chun-Tse Shao Committed by Arnaldo Carvalho de Melo
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perf test: Allow tolerance for leader sampling test 



There is a known issue that the leader sampling is inconsistent, since
throttle only affect leader, not the slave. The detail is in [1].

To maintain test coverage, this patch sets a tolerance rate of 80% to
accommodate the throttled samples and prevent test failures due to
throttling.

[1] lore.kernel.org/20250328182752.769662-1-ctshao@google.com

Suggested-by: default avatarIan Rogers <irogers@google.com>
Suggested-by: default avatarThomas Richter <tmricht@linux.ibm.com>
Reviewed-by: default avatarIan Rogers <irogers@google.com>
Signed-off-by: default avatarChun-Tse Shao <ctshao@google.com>
Co-developed-by: default avatarThomas Richter <tmricht@linux.ibm.com>
Signed-off-by: default avatarThomas Richter <tmricht@linux.ibm.com>
Tested-by: default avatarThomas Richter <tmricht@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: https://lore.kernel.org/r/20250430140611.599078-1-tmricht@linux.ibm.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent cb422594

tools/perf/tests/shell/record.sh

+27 −6
Original line number Diff line number Diff line
@@ -240,22 +240,43 @@ test_leader_sampling() { 
    err=1

    return

  fi

  perf script -i "${perfdata}" | grep brstack > $script_output

  # Check if the two instruction counts are equal in each record.

  # However, the throttling code doesn't consider event grouping. During throttling, only the

  # leader is stopped, causing the slave's counts significantly higher. To temporarily solve this,

  # let's set the tolerance rate to 80%.

  # TODO: Revert the code for tolerance once the throttling mechanism is fixed.

  index=0

  perf script -i "${perfdata}" > "${script_output}"

  valid_counts=0

  invalid_counts=0

  tolerance_rate=0.8

  while IFS= read -r line

  do

    # Check if the two instruction counts are equal in each record

    cycles=$(echo $line | awk '{for(i=1;i<=NF;i++) if($i=="cycles:") print $(i-1)}')

    if [ $(($index%2)) -ne 0 ] && [ ${cycles}x != ${prev_cycles}x ]

    then

      echo "Leader sampling [Failed inconsistent cycles count]"

      err=1

      return

      invalid_counts=$(($invalid_counts+1))

    else

      valid_counts=$(($valid_counts+1))

    fi

    index=$(($index+1))

    prev_cycles=$cycles

  done < "${script_output}"

  total_counts=$(bc <<< "$invalid_counts+$valid_counts")

  if (( $(bc <<< "$total_counts <= 0") ))

  then

    echo "Leader sampling [No sample generated]"

    err=1

    return

  fi

  isok=$(bc <<< "scale=2; if (($invalid_counts/$total_counts) < (1-$tolerance_rate)) { 0 } else { 1 };")

  if [ $isok -eq 1 ]

  then

     echo "Leader sampling [Failed inconsistent cycles count]"

     err=1

  else

    echo "Basic leader sampling test [Success]"

  fi

}



test_topdown_leader_sampling() {