> On Mar 17, 2021, at 11:07 PM, Namhyung Kim wrote:
>
> On Wed, Mar 17, 2021 at 6:18 AM Song Liu wrote:
>>
>> Add a test to compare the output of perf-stat with and without option
>> --bpf-counters. If the difference is more than 10%, the test is considered
>> as failed.
>>
>> For stable results between two runs (w/ and w/o --bpf-counters), the test
>> program should: 1) be long enough for better signal-noise-ratio; 2) not
>> depend on the behavior of IO subsystem (for less noise from caching). So
>> far, the best option we found is stressapptest.
>>
>> Signed-off-by: Song Liu
>> ---
>> tools/perf/tests/shell/stat_bpf_counters.sh | 34 +
>> 1 file changed, 34 insertions(+)
>> create mode 100755 tools/perf/tests/shell/stat_bpf_counters.sh
>>
>> diff --git a/tools/perf/tests/shell/stat_bpf_counters.sh
>> b/tools/perf/tests/shell/stat_bpf_counters.sh
>> new file mode 100755
>> index 0..c0bcb38d6b53c
>> --- /dev/null
>> +++ b/tools/perf/tests/shell/stat_bpf_counters.sh
>> @@ -0,0 +1,34 @@
>> +#!/bin/sh
>> +# perf stat --bpf-counters test
>> +# SPDX-License-Identifier: GPL-2.0
>> +
>> +set -e
>> +
>> +# check whether $2 is within +/- 10% of $1
>> +compare_number()
>> +{
>> + first_num=$1
>> + second_num=$2
>> +
>> + # upper bound is first_num * 110%
>> + upper=$(( $first_num + $first_num / 10 ))
>> + # lower bound is first_num * 90%
>> + lower=$(( $first_num - $first_num / 10 ))
>> +
>> + if [ $second_num -gt $upper ] || [ $second_num -lt $lower ]; then
>> + echo "The difference between $first_num and $second_num are
>> greater than 10%."
>> + exit 1
>> + fi
>> +}
>> +
>> +# skip if --bpf-counters is not supported
>> +perf stat --bpf-counters true > /dev/null 2>&1 || exit 2
>> +
>> +# skip if stressapptest is not available
>> +stressapptest -s 1 -M 100 -m 1 > /dev/null 2>&1 || exit 2
>
> I don't know how popular it is, but we can print some info
> in case we miss it.
I just realized that perf-bench-sched-messaging is a good test to use,
so we don't need stressapptest. Attached the updated version below.
>
>> +
>> +base_cycles=$(perf stat --no-big-num -e cycles -- stressapptest -s 3 -M 100
>> -m 1 2>&1 | grep -e cycles | awk '{print $1}')
>> +bpf_cycles=$(perf stat --no-big-num --bpf-counters -e cycles --
>> stressapptest -s 3 -M 100 -m 1 2>&1 | grep -e cycles | awk '{print $1}')
>
> I think just awk '/cycles/ {print $1}' should work.
Thanks! Fixed in the new version.
Song
cat tools/perf/tests/shell/stat_bpf_counters.sh
#!/bin/sh
# perf stat --bpf-counters test
# SPDX-License-Identifier: GPL-2.0
set -e
# check whether $2 is within +/- 10% of $1
compare_number()
{
first_num=$1
second_num=$2
# upper bound is first_num * 110%
upper=$(( $first_num + $first_num / 10 ))
# lower bound is first_num * 90%
lower=$(( $first_num - $first_num / 10 ))
if [ $second_num -gt $upper ] || [ $second_num -lt $lower ]; then
echo "The difference between $first_num and $second_num are
greater than 10%."
exit 1
fi
}
# skip if --bpf-counters is not supported
perf stat --bpf-counters true > /dev/null 2>&1 || exit 2
base_cycles=$(perf stat --no-big-num -e cycles -- perf bench sched messaging -g
1 -l 100 -t 2>&1 | awk '/cycles/ {print $1}')
bpf_cycles=$(perf stat --no-big-num --bpf-counters -e cycles -- perf bench
sched messaging -g 1 -l 100 -t 2>&1 | awk '/cycles/ {print $1}')
compare_number $base_cycles $bpf_cycles
exit 0
