linux-kernel - Re: [PATCH 1/2 v2] perf test: Fix perf test 114 perf record test subtest precise

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Message-ID: <a39b5e6c-4096-4d0f-8c1a-8fcc5678c012@linaro.org>
Date: Wed, 29 Jan 2025 11:11:26 +0000
From: James Clark <james.clark@...aro.org>
To: Thomas Richter <tmricht@...ux.ibm.com>, namhyung@...nel.org
Cc: agordeev@...ux.ibm.com, gor@...ux.ibm.com, sumanthk@...ux.ibm.com,
 hca@...ux.ibm.com, linux-kernel@...r.kernel.org,
 linux-perf-users@...r.kernel.org, acme@...nel.org
Subject: Re: [PATCH 1/2 v2] perf test: Fix perf test 114 perf record test
 subtest precise_max for s390



On 29/01/2025 9:57 am, James Clark wrote:
> 
> Is this a v2 of "[PATCH] perf test: Fix perf test 114 perf record test 
> for s390"? Or maybe the v2 is a typo?
> 

Nevermind, the CC list is different on the two patches that's why I got 
confused.

> On 29/01/2025 7:11 am, Thomas Richter wrote:
>> On s390 the event instructions can not be used for recording.
>> This event is only supported by perf stat.
>>
>> Change the event instruction to cycles for subtest test_precise_max
>> as suggested by James Clark.
>>
>> Signed-off-by: Thomas Richter <tmricht@...ux.ibm.com>
>> Suggested-by: James Clark <james.clark@...aro.org>
>> ---
>>   tools/perf/tests/shell/record.sh | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/perf/tests/shell/record.sh b/tools/perf/tests/ 
>> shell/record.sh
>> index 0fc7a909ae9b..957ee10aff44 100755
>> --- a/tools/perf/tests/shell/record.sh
>> +++ b/tools/perf/tests/shell/record.sh
>> @@ -287,9 +287,9 @@ test_precise_max() {
>>       return
>>     fi
>>     # On AMD, cycles and instructions events are treated differently
>> -  if ! perf record -o "${perfdata}" -e "instructions:P" true 2> /dev/ 
>> null
>> +  if ! perf record -o "${perfdata}" -e "cycles:P" true 2> /dev/null
> 
> I'm not sure if this is the right fix. Doesn't this make the test test 
> cycles:P twice now?
> 
> I think the fix is to first test if cycles can be sampled, then test 
> cycles:P. Then test if instructions can be sampled, then test 
> instructions:P.
> 
> At the moment it checks the events with perf stat, and it checks them 
> both at the same time. Obviously that doesn't work if an event works for 
> perf stat but not perf record. And checking them both at the same time 
> doesn't allow for one existing and not the other.
> 
>>     then
>> -    echo "precise_max attribute [Failed instructions:P event]"
>> +    echo "precise_max attribute [Failed cycles:P event]"
>>       err=1
>>       return
>>     fi
>