linux-kernel - Re: [PATCH V3 0/7] Clean up perf mem

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Message-ID: <ceffdc69-982b-4909-95df-5b6a8a277f20@linux.ibm.com>
Date: Tue, 23 Jan 2024 06:56:29 +0100
From: Thomas Richter <tmricht@...ux.ibm.com>
To: kajoljain <kjain@...ux.ibm.com>, "Liang, Kan"
 <kan.liang@...ux.intel.com>,
        acme@...nel.org, irogers@...gle.com, peterz@...radead.org,
        mingo@...hat.com, namhyung@...nel.org, jolsa@...nel.org,
        adrian.hunter@...el.com, john.g.garry@...cle.com, will@...nel.org,
        james.clark@....com, mike.leach@...aro.org, leo.yan@...aro.org,
        yuhaixin.yhx@...ux.alibaba.com, renyu.zj@...ux.alibaba.com,
        ravi.bangoria@....com, atrajeev@...ux.vnet.ibm.com,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH V3 0/7] Clean up perf mem

On 1/23/24 06:30, kajoljain wrote:
> 
> 
> On 1/16/24 22:07, Liang, Kan wrote:
>>
>>
>> On 2024-01-16 9:05 a.m., kajoljain wrote:
>>>> For powerpc, the patch 3 introduced a perf_mem_events_power, which
>>>> doesn't have ldlat. But it only be assigned to the pmu->is_core. I'm not
>>>> sure if it's the problem.
>>> Hi Kan,
>>>  Correct there were some small issues with patch 3, I added fix for that.
>>>
>>
>> Thanks Kajol Jain! I will fold your fix into V4.
>>
>>>> Also, S390 still uses the default perf_mem_events, which includes ldlat.
>>>> I'm not sure if S390 supports the ldlat.
>>> I checked it, I didn't find ldlat parameter defined in arch/s390
>>> directory. I think its better to make default ldlat value as false
>>> in tools/perf/util/mem-events.c file.
>>
>> The s390 may not be the only user for the default perf_mem_events[] in
>> the tools/perf/util/mem-events.c. We probably cannot change the default
>> value.
>> We may share the perf_mem_events_power[] between powerpc and s390. (We
>> did the similar share for arm and arm64.)
>>
>> How about the below patch (not tested.)
>>
>> diff --git a/tools/perf/arch/s390/util/pmu.c
>> b/tools/perf/arch/s390/util/pmu.c
>> index 225d7dc2379c..411034c984bb 100644
>> --- a/tools/perf/arch/s390/util/pmu.c
>> +++ b/tools/perf/arch/s390/util/pmu.c
>> @@ -8,6 +8,7 @@
>>  #include <string.h>
>>
>>  #include "../../../util/pmu.h"
>> +#include "../../powerpc/util/mem-events.h"
>>
>>  #define        S390_PMUPAI_CRYPTO      "pai_crypto"
>>  #define        S390_PMUPAI_EXT         "pai_ext"
>> @@ -21,5 +22,5 @@ void perf_pmu__arch_init(struct perf_pmu *pmu)
>>                 pmu->selectable = true;
>>
>>         if (pmu->is_core)
>> -               pmu->mem_events = perf_mem_events;
>> +               pmu->mem_events = perf_mem_events_power;
>>  }
>>
>>
>>
>> However, the original s390 code doesn't include any s390 specific code
>> for perf_mem. So I thought it uses the default perf_mem_events[].
>> Is there something I missed?
>>
>> Or does the s390 even support mem events? If not, I may remove the
>> mem_events from s390.
> 
> Hi Kan,
>    I don't have s390 system to do testing. But from my end I am fine
> with the changes.
> 
> Thanks,
> Kajol Jain
> 

s390 does not support perf mem at all. Right now it is save to remove it from s390.
Thanks

>>
>> Thanks,
>> Kan
> 

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

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