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

[Vikas Shivappa]

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@xxxxxxxxxxxxxxx>
> > AuthorDate: Thu, 10 Mar 2016 15:32:07 -0800
> > Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
> > 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

>