linux-kernel - Re: [PATCH v3] perf/x86/intel/uncore: Fix CAS_COUNT

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Message-ID: <9a163f6a-ea8e-45cb-238a-ded1b2218e3d@linux.intel.com>
Date:   Thu, 23 Dec 2021 09:33:17 +0800
From:   Xing Zhengjun <zhengjun.xing@...ux.intel.com>
To:     "Liang, Kan" <kan.liang@...ux.intel.com>, peterz@...radead.org,
        mingo@...hat.com, acme@...nel.org, linux-kernel@...r.kernel.org
Cc:     adrian.hunter@...el.com, alexander.shishkin@...el.com,
        ak@...ux.intel.com, kan.liang@...el.com, stable@...r.kernel.org
Subject: Re: [PATCH v3] perf/x86/intel/uncore: Fix CAS_COUNT_WRITE issue for
 ICX



On 12/23/2021 12:30 AM, Liang, Kan wrote:
> 
> 
> On 11/18/2021 11:02 AM, zhengjun.xing@...ux.intel.com wrote:
>> From: Zhengjun Xing <zhengjun.xing@...ux.intel.com>
>>
>> The user recently report a perf issue in the ICX platform, when test by
> 
> If you have the user's name, you may want to add a Reported-by tag to 
> give them credit. If you don't have, it doesn't matter either.
> 
Unfortunately, I haven't the exactly user's name.

>> perf event “uncore_imc_x/cas_count_write”,the write bandwidth is always
>> very small (only 0.38MB/s), it is caused by the wrong "umask" for the
>> "cas_count_write" event. When double-checking, find "cas_count_read"
>> also is wrong.
>>
>> The public document for ICX uncore:
>>
>> https://www.intel.com/content/www/us/en/develop/download/3rd-gen-intel-xeon-processor-scalable-uncore-pm.html 
>>
>>
>> On page 142, Table 2-143, defines Unit Masks for CAS_COUNT:
>> RD b00001111
>> WR b00110000
>>
> 
> I think we usually want a permanent reference in the change log. The 
> document may be updated later. The page number or the table number may 
> not be accurate anymore.
> 
> I guess you may want to give the exact document name and the version 
> number here. So people can still easily locate the information several 
> years later.
> E.g., "3rd Gen Intel® Xeon® Processor Scalable Family, Codename Ice 
> Lake, Uncore Performance Monitoring Reference Manual, Revision 1.00, May 
> 2021"
> 
>
Thanks, I will update it in the new version patch.

>> So Corrected both "cas_count_read" and "cas_count_write" for ICX.
>>
>> Old settings:
>>   hswep_uncore_imc_events
>>     INTEL_UNCORE_EVENT_DESC(cas_count_read,  "event=0x04,umask=0x03")
>>       INTEL_UNCORE_EVENT_DESC(cas_count_write, "event=0x04,umask=0x0c")
>>
>> New settings:
>>   snr_uncore_imc_events
>>     INTEL_UNCORE_EVENT_DESC(cas_count_read,  "event=0x04,umask=0x0f")
>>     INTEL_UNCORE_EVENT_DESC(cas_count_write, "event=0x04,umask=0x30"),
>>
>> Fixes: 2b3b76b5ec67 ("perf/x86/intel/uncore: Add Ice Lake server 
>> uncore support")
>> Reviewed-by: Adrian Hunter <adrian.hunter@...el.com>
> 
> Other than the above comments, the patch looks good to me.
> 
> Reviewed-by: Kan Liang <kan.liang@...ux.intel.com>
> 
> 
> Thanks,
> Kan
> 
>> Signed-off-by: Zhengjun Xing <zhengjun.xing@...ux.intel.com>
>> Cc: stable@...r.kernel.org
>> ---
>> Change log:
>>
>>    v3:
>>      * Add change log
>>
>>    v2:
>>      * Add stable tag
>>
>>   arch/x86/events/intel/uncore_snbep.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/events/intel/uncore_snbep.c 
>> b/arch/x86/events/intel/uncore_snbep.c
>> index 5ddc0f30db6f..a6fd8eb410a9 100644
>> --- a/arch/x86/events/intel/uncore_snbep.c
>> +++ b/arch/x86/events/intel/uncore_snbep.c
>> @@ -5468,7 +5468,7 @@ static struct intel_uncore_type icx_uncore_imc = {
>>       .fixed_ctr_bits    = 48,
>>       .fixed_ctr    = SNR_IMC_MMIO_PMON_FIXED_CTR,
>>       .fixed_ctl    = SNR_IMC_MMIO_PMON_FIXED_CTL,
>> -    .event_descs    = hswep_uncore_imc_events,
>> +    .event_descs    = snr_uncore_imc_events,
>>       .perf_ctr    = SNR_IMC_MMIO_PMON_CTR0,
>>       .event_ctl    = SNR_IMC_MMIO_PMON_CTL0,
>>       .event_mask    = SNBEP_PMON_RAW_EVENT_MASK,

-- 
Zhengjun Xing