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

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Date: Tue, 23 Jan 2024 09:36:37 -0500
From: "Liang, Kan" <kan.liang@...ux.intel.com>
To: Thomas Richter <tmricht@...ux.ibm.com>, kajoljain <kjain@...ux.ibm.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 2024-01-23 12:56 a.m., Thomas Richter wrote:
> 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 for the confirmation!

Thanks,
Kan

> Thanks
> 
>>>
>>> Thanks,
>>> Kan
>>
>