linux-kernel - Re: [PATCH] perf test: Fix test perf stat tests for virtualized machines

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Message-ID: <0f55cde3-cba0-4e43-b2ac-1f1b506f4e15@linux.ibm.com>
Date: Wed, 7 Jan 2026 14:01:06 +0100
From: Thomas Richter <tmricht@...ux.ibm.com>
To: James Clark <james.clark@...aro.org>
Cc: agordeev@...ux.ibm.com, gor@...ux.ibm.com, sumanthk@...ux.ibm.com,
        hca@...ux.ibm.com, japo@...ux.ibm.com, linux-kernel@...r.kernel.org,
        linux-s390@...r.kernel.org, linux-perf-users@...r.kernel.org,
        acme@...nel.org, namhyung@...nel.org, irogers@...gle.com
Subject: Re: [PATCH] perf test: Fix test perf stat tests for virtualized
 machines

On 1/7/26 12:18, James Clark wrote:
> 
> 
> On 07/01/2026 9:48 am, Thomas Richter wrote:
>> On s390 perf test 'perf stat tests', subtest test_hybrid fails
>> for z/VM systems.
>> The root cause is this statement:
>>
>>    $(perf stat -a -- sleep 0.1 2>&1 |\
>>                    grep -E "/cpu-cycles/[uH]*|  cpu-cycles[:uH]* -c)
>>
>> The perf stat output on a s390 z/VM system is
>>
>>   # perf stat -a -- sleep 0.1 2>&1
>>   Performance counter stats for 'system wide':
>>
>>         56      context-switches  #     46.3 cs/sec  cs_per_second
>>   1,210.41 msec cpu-clock         #     11.9 CPUs  CPUs_utilized
>>         12      cpu-migrations    #      9.9 migrations/sec ...
>>         81      page-faults       #     66.9 faults/sec ...
>>
>>         0.100891009 seconds time elapsed
>>
>> The grep command does not match any single line and exits with error
>> code 1. As the bash script is executed with set -e, it aborts with the
>> first error code being non-zero.
>>
>> Fix this and use wc -l to count matching lines instead of grep ... -c.
>>
>> Output before:
>>   # perf test 102
>>   102: perf stat tests                      : FAILED!
>>   #
>> Output after:
>>   # perf test 102
>>   102: perf stat tests                      : Ok
>>   #
>>
>> Fixes: 65d11821910bd ("perf test: Add a test for default perf stat command")
> 
> I think the change looks ok, but doesn't it fix 65d11821910bd ("perf tools: Add fallback for exclude_guest") where the existing wc -l was changed to grep -c?
> 

You are correct, James.
I will send V2 with updated Fixes tag.

Thanks
-- 
Thomas Richter, Dept 3303, IBM s390 Linux Development, Boeblingen, Germany
--
IBM Deutschland Research & Development GmbH

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