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From: Matt Fleming <matt@console-pimps.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>, Jiri Olsa <jolsa@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Matt Fleming <matt.fleming@intel.com>,
	Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: [PATCH 10/11] perf/x86/intel: Support task events with Intel CQM
Date: Fri, 10 Oct 2014 13:02:02 +0100	[thread overview]
Message-ID: <20141010120202.GY14343@console-pimps.org> (raw)
In-Reply-To: <20141008144957.GK10832@worktop.programming.kicks-ass.net>

On Wed, 08 Oct, at 04:49:57PM, Peter Zijlstra wrote:
> 
> 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.

For CQM it's not about "fitting" everything in the PMU but more about
monitoring the same thing (task, cgroup) with different events, i.e. one
thing with two RMIDs. We have the RMID recycling algorithm to make
things fit, but that doesn't help us out here.

An example scenario that isn't supported by this patch series is
monitoring a cgroup while simultaneously monitoring a task that's part
of that cgroup. Whichever event is created second will fail at event
init time.

And that seemed like a fair approach to me. But the more I think about
it, the more I begin to agree that maybe we should allow users the
flexibility to create conflicting events, particularly because there
appears to be precedent in other parts of perf.

Hmm... "rotation" is starting to become my least favourite word.

-- 
Matt Fleming, Intel Open Source Technology Center

  reply	other threads:[~2014-10-10 12:02 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-24 14:04 [PATCH 00/11] perf: Intel Cache QoS Monitoring support Matt Fleming
2014-09-24 14:04 ` [PATCH 01/11] perf stat: Fix AGGR_CORE segfault on multi-socket system Matt Fleming
2014-09-24 14:04 ` [PATCH 02/11] perf tools: Refactor unit and scale function parameters Matt Fleming
2014-09-29  9:21   ` Jiri Olsa
2014-10-03  5:25   ` [tip:perf/core] " tip-bot for Matt Fleming
2014-09-24 14:04 ` [PATCH 03/11] perf tools: Parse event per-package info files Matt Fleming
2014-09-24 14:04 ` [PATCH 04/11] perf: Make perf_cgroup_from_task() global Matt Fleming
2014-10-07 18:51   ` Peter Zijlstra
2014-10-08 10:27     ` Matt Fleming
2014-09-24 14:04 ` [PATCH 05/11] perf: Add ->count() function to read per-package counters Matt Fleming
2014-09-24 14:04 ` [PATCH 06/11] perf: Move cgroup init before PMU ->event_init() Matt Fleming
2014-10-07 19:34   ` Peter Zijlstra
2014-10-08 10:32     ` Matt Fleming
2014-10-08 10:49       ` Peter Zijlstra
2014-09-24 14:04 ` [PATCH 07/11] x86: Add support for Intel Cache QoS Monitoring (CQM) detection Matt Fleming
2014-09-24 14:04 ` [PATCH 08/11] perf/x86/intel: Add Intel Cache QoS Monitoring support Matt Fleming
2014-09-24 16:40   ` Andi Kleen
2014-09-24 20:27     ` Matt Fleming
2014-09-24 20:39       ` Andi Kleen
2014-09-29 18:51         ` Matt Fleming
2014-10-07 19:43   ` Peter Zijlstra
2014-10-08 10:36     ` Matt Fleming
2014-10-08 12:15       ` Matt Fleming
2014-10-08 14:47         ` Peter Zijlstra
2014-10-08 20:51           ` Peter Zijlstra
2014-09-24 14:04 ` [PATCH 09/11] perf/x86/intel: Implement LRU monitoring ID allocation for CQM Matt Fleming
2014-10-08  9:51   ` Peter Zijlstra
2014-10-08 10:53     ` Matt Fleming
2014-09-24 14:04 ` [PATCH 10/11] perf/x86/intel: Support task events with Intel CQM Matt Fleming
2014-09-24 14:45   ` Matt Fleming
2014-10-08 10:01   ` Peter Zijlstra
2014-10-08 11:07   ` Peter Zijlstra
2014-10-08 12:10     ` Matt Fleming
2014-10-08 14:49       ` Peter Zijlstra
2014-10-10 12:02         ` Matt Fleming [this message]
2014-10-10 14:02           ` Peter Zijlstra
2014-10-10 10:54     ` Peter Zijlstra
2014-10-10 11:10       ` Matt Fleming
2014-09-24 14:04 ` [PATCH 11/11] perf/x86/intel: Perform rotation on Intel CQM RMIDs Matt Fleming
2014-10-08 11:19   ` Peter Zijlstra
2014-10-08 11:56     ` Matt Fleming
2014-10-08 18:08   ` Peter Zijlstra
2014-10-08 19:02     ` Thomas Gleixner
2014-10-08 19:59       ` Matt Fleming
2014-10-08 18:10   ` Peter Zijlstra
2014-10-08 20:04     ` Matt Fleming

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