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

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Date:	Tue, 7 Oct 2014 21:43:10 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Matt Fleming <matt@...sole-pimps.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 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.


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