linux-kernel - Re: [PATCH 10/11] perf/x86/intel: Support task events with Intel CQM

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Message-ID: <20141008144957.GK10832@worktop.programming.kicks-ass.net>
Date:	Wed, 8 Oct 2014 16:49:57 +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 10/11] perf/x86/intel: Support task events with Intel CQM

On Wed, Oct 08, 2014 at 01:10:44PM +0100, Matt Fleming wrote:
> Ah, interesting.
> 
> I dropped the internal scheduling because I preferred the idea of
> "failing fast", in the sense that if we can't schedule multiple events
> simultaneously because they conflict, we should report that to the user
> at event init time, rather than trying to manage the conflict ourselves,
> with the resultant loss of accuracy.

The thing is, with multiplexing you cannot fail at event creation time
anyhow. The only time where you can 'fail' is when programming the PMU,
when its full its full.

Those that don't fit, get to wait their turn.
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