linux-kernel - Re: [PATCH 08/11] perf/x86/intel: Add Intel Cache QoS Monitoring support

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Date:	Wed, 8 Oct 2014 11:36:58 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Ingo Molnar <mingo@...nel.org>, Jiri Olsa <jolsa@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
	Matt Fleming <matt.fleming@...el.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH 08/11] perf/x86/intel: Add Intel Cache QoS Monitoring
 support

On Tue, 07 Oct, at 09:43:10PM, Peter Zijlstra wrote:
> On Wed, Sep 24, 2014 at 03:04:12PM +0100, Matt Fleming wrote:
> > +/*
> > + * Determine if @a and @b measure the same set of tasks.
> > + */
> > +static bool __match_event(struct perf_event *a, struct perf_event *b)
> > +{
> > +	if ((a->attach_state & PERF_ATTACH_TASK) !=
> > +	    (b->attach_state & PERF_ATTACH_TASK))
> > +		return false;
> > +
> > +	/* not task */
> > +
> > +	return true; /* if not task, we're machine wide */
> > +}
> 
> You cut too much out there. That first test checks weather the two
> events are of the same type; ie. both tasks or both cpu. After that you
> still need to verify that they are indeed the same target.

This gets fixed in PATCH 10 where we actually implement monitoring of
task events. At this point in the series, we'll return -EINVAL from
intel_cqm_event_init() for anything other than a cpu event.

-- 
Matt Fleming, Intel Open Source Technology Center
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