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SubjectRe: [tip:perf/urgent] perf/x86/cqm: Fix CQM handling of grouping events into a cache_group


On Mon, 21 Mar 2016, Matt Fleming wrote:

> On Mon, 21 Mar, at 02:51:29AM, tip-bot for Vikas Shivappa wrote:
>> Commit-ID: a223c1c7ab4cc64537dc4b911f760d851683768a
>> Gitweb: http://git.kernel.org/tip/a223c1c7ab4cc64537dc4b911f760d851683768a
>> Author: Vikas Shivappa <vikas.shivappa@linux.intel.com>
>> AuthorDate: Thu, 10 Mar 2016 15:32:07 -0800
>> Committer: Ingo Molnar <mingo@kernel.org>
>> CommitDate: Mon, 21 Mar 2016 09:08:18 +0100
>>
>> perf/x86/cqm: Fix CQM handling of grouping events into a cache_group
>>
>> Currently CQM (cache quality of service monitoring) is grouping all
>> events belonging to same PID to use one RMID. However its not counting
>> all of these different events. Hence we end up with a count of zero
>> for all events other than the group leader.
>
> The reason that was done originally was because reporting for all events
> in a group led to duplicate values, since you'd be emitting the same
> RMID value multiple times.
>
> Is this no longer a problem?

Before MBM , the below condition was never hit because we had only one event ?

- if (a->hw.target == b->hw.target)
+ if (a->hw.target == b->hw.target) {
+ b->hw.is_group_event = true;

We are trying to address this for cases where different MBM(local or total) and
cqm events are grouped into one RMID.

Which is the case which led to duplicate values ?

Thanks,
Vikas

>

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