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SubjectRe: [LKP] Re: [perf x86] b77491648e: will-it-scale.per_process_ops -2.1% regression
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On 2/12/2020 5:56 AM, Chen, Rong A wrote:
>
>
> On 2/6/2020 4:47 AM, Andi Kleen wrote:
>> kernel test robot <rong.a.chen@intel.com> writes:
>>
>>> Greeting,
>>>
>>> FYI, we noticed a -2.1% regression of will-it-scale.per_process_ops
>>> due to commit:
>>>
>>>
>>> commit: b77491648e6eb2f26b6edf5eaea859adc17f4dcc ("perf x86:
>>> Infrastructure for exposing an Uncore unit to PMON mapping")
>>> https://github.com/0day-ci/linux/commits/roman-sudarikov-linux-intel-com/perf-x86-Exposing-IO-stack-to-IO-PMON-mapping-through-sysfs/20200118-075508
>>>
>> Seems to be spurious bisect. I don't think that commit could change
>> anything performance related.
>
> Hi Andi,
>
> I commented out some lines in arch/x86/events/intel/uncore.c and
> will-it-scale.per_process_ops increased.
>
> commit:
>   v5.4
>   b77491648e ("perf x86: Infrastructure for exposing an Uncore unit to
> PMON mapping")
>   f33fe1b258 ("test")
>
>
>             v5.4  b77491648e6eb2f26b6edf5eae
> f33fe1b258b2a4b2fc97600b2b  testcase/testparams/testbox
> ----------------  -------------------------- --------------------------
> ---------------------------
>          %stddev      change         %stddev      change %stddev
>              \          |                \          | \
>      47983                       47004 47647
> will-it-scale/performance-process-100%-signal1-ucode=0xb000038/lkp-bdw-ep6
>      47983                       47004 47647        GEO-MEAN
> will-it-scale.per_process_ops
>
> diff --git a/arch/x86/events/intel/uncore.c
> b/arch/x86/events/intel/uncore.c
> index 55201bfde2c84c..0dc9c455423d99 100644
> --- a/arch/x86/events/intel/uncore.c
> +++ b/arch/x86/events/intel/uncore.c
> @@ -887,7 +887,7 @@ static int uncore_pmu_register(struct
> intel_uncore_pmu *pmu)
>                 pmu->pmu.attr_groups = pmu->type->attr_groups;
>         }
>
> -       pmu->pmu.attr_update = attr_update;
> +       // pmu->pmu.attr_update = attr_update;
>
>         if (pmu->type->num_boxes == 1) {
>                 if (strlen(pmu->type->name) > 0)
> @@ -903,7 +903,7 @@ static int uncore_pmu_register(struct
> intel_uncore_pmu *pmu)
>          * Exposing mapping of Uncore units to corresponding Uncore PMUs
>          * through /sys/devices/uncore_<type>_<idx>/mapping
>          */
> -       uncore_platform_mapping(pmu->type);
> +       // uncore_platform_mapping(pmu->type);

The patch is for SKX uncore. The test machine looks like a BDX.
So the mapping_group should always be invisible.
The attr_update should not update.
I think there should be no performance impact.

static void uncore_platform_mapping(struct intel_uncore_type *t)
{
if (t->get_topology && t->set_mapping &&
!t->get_topology(t, max_dies) && !t->set_mapping(t, max_dies))
mapping_group.is_visible = NULL;
else
mapping_group.is_visible = not_visible;
}

Kan

>
>         ret = perf_pmu_register(&pmu->pmu, pmu->name, -1);
>         if (!ret)
>
> Best Regards,
> Rong Chen
>
>>
>> -Andi
>> _______________________________________________
>> LKP mailing list -- lkp@lists.01.org
>> To unsubscribe send an email to lkp-leave@lists.01.org
>

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