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

[Matt Fleming]

On Mon, 21 Mar, at 11:14:37AM, Vikas Shivappa wrote:
> 
> 
> 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.
 
I can't test these changes, so I'm only working from memory, but I
seem to recall that this condition is hit if monitoring simultaneously
from two invocations of perf. It's also possible to have pid/tid
groups overlapping, and that needs to be handled.

> Which is the case which led to duplicate values ?

Good question. Try monitoring a multithread process with these changes
and see if you get duplicate values reported.