Date: Wed, 23 Mar 2016 20:14:38 +0000
From: Matt Fleming <matt@codeblueprint.co.uk>
To: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Cc: hpa@zytor.com, eranian@google.com, linux-kernel@vger.kernel.org,
        tony.luck@intel.com, brgerst@gmail.com, peterz@infradead.org,
        bp@alien8.de, tglx@linutronix.de, dsahern@gmail.com,
        dvlasenk@redhat.com, jolsa@redhat.com, luto@amacapital.net,
        mingo@kernel.org, acme@redhat.com, torvalds@linux-foundation.org,
        namhyung@kernel.org, vincent.weaver@maine.edu,
        alexander.shishkin@linux.intel.com, linux-tip-commits@vger.kernel.org
Subject: Re: [tip:perf/urgent] perf/x86/cqm: Fix CQM handling of grouping
 events into a cache_group
Message-ID: <20160323201438.GH11676@codeblueprint.co.uk>
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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.