linux-kernel - Re: [PATCH] perf/x86/intel/uncore: Fix client IMC events return huge result

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Date:   Fri, 16 Nov 2018 11:32:35 -0500
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Sasha Levin <sashal@...nel.org>
Cc:     tglx@...utronix.de, peterz@...radead.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        yao.jin@...ux.intel.com, stable@...r.kernel.org
Subject: Re: [PATCH] perf/x86/intel/uncore: Fix client IMC events return huge
 result



On 11/16/2018 11:12 AM, Sasha Levin wrote:
> On Fri, Nov 16, 2018 at 05:19:45AM -0800, kan.liang@...ux.intel.com wrote:
>> From: Kan Liang <kan.liang@...ux.intel.com>
>>
>> The client IMC bandwidth events return very huge result.
>>  perf stat -e uncore_imc/data_reads/ -e uncore_imc/data_writes/ -I
>> 10000 -a
>>  10.000117222 34,788.76 MiB uncore_imc/data_reads/
>>  10.000117222 8.26 MiB uncore_imc/data_writes/
>>  20.000374584 34,842.89 MiB uncore_imc/data_reads/
>>  20.000374584 10.45 MiB uncore_imc/data_writes/
>>  30.000633299 37,965.29 MiB uncore_imc/data_reads/
>>  30.000633299 323.62 MiB uncore_imc/data_writes/
>>  40.000891548 41,012.88 MiB uncore_imc/data_reads/
>>  40.000891548 6.98 MiB uncore_imc/data_writes/
>>  50.001142480 1,125,899,906,621,494.75 MiB uncore_imc/data_reads/
>>  50.001142480 6.97 MiB uncore_imc/data_writes/
>>
>> The client IMC events are freerunning counters. They still use the
>> old event encoding format (0x1 for data_read and 0x2 for data write).
>> The counter bit width is calculated by common code, which assume that
>> the standard encoding format is used for the freerunning counters.
>> Error bit width information is calculated.
>>
>> The event->attr.config, which directly from user space, should not be
>> used by the functions of freerunning counters.
>> For client IMC events, the attr.config needs to be converted to the
>> standard encoding format. The modified event config will be stored in
>> event->hw.config.
>> For other freerunning counters, the attr.config has the correct format.
>> Just save it in event->hw.config.
>> Using event->hw.config to replace event->attr.config for the functions
>> of freerunning counters.
>>
>> Fix: commit 9aae1780e7e8 ("perf/x86/intel/uncore: Clean up client IMC
>> uncore")
> 
> Please use a "fixes" (vs "fix") tag here, a few folks have automation
> around this. It should look something like this:
> 
>      Fixes: commit 9aae1780e7e8 ("perf/x86/intel/uncore: Clean up client 
> IMC uncore")
> 
> Also, if you intend for this to go in stable trees, please add a stable
> tag rather than just cc it to the stable mailing list. Something like
> this:
> 
>      Cc: stable@...nel.org
>

Thanks Sasha for the review. I have sent a V2 patch to address the 
format issue.

Thanks,
Kan