linux-kernel - Re: [PATCH 4/4] perf/x86/cqm: Support cqm/mbm only for perf events

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Message-ID: <20160425091805.GG3430@twins.programming.kicks-ass.net>
Date:	Mon, 25 Apr 2016 11:18:05 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Vikas Shivappa <vikas.shivappa@...ux.intel.com>
Cc:	tony.luck@...el.com, ravi.v.shankar@...el.com,
	fenghua.yu@...el.com, vikas.shivappa@...el.com, x86@...nel.org,
	linux-kernel@...r.kernel.org, hpa@...or.com, tglx@...utronix.de,
	mingo@...nel.org, h.peter.anvin@...el.com
Subject: Re: [PATCH 4/4] perf/x86/cqm: Support cqm/mbm only for perf events

On Fri, Apr 22, 2016 at 05:27:21PM -0700, Vikas Shivappa wrote:
> The cgroup support for cqm is broken. Instead of mapping RMID to a
> cgroup currently its mapped to the task and then hence when task moves
> cgroup we get incorrect count.
> 
> Also the conflict handling code which is meant to handle the case of
> co-existing cgroup and task events, is broken. It reports very
> confusing numbers of intermittent zero and some occupancy when perf is
> run with cgroup and task events.
> 
> Hence removing support for the parts which are broken rather than
> pretending to support it and giving incorrect data.

Uh what, how about attempt to fix it?