linux-kernel - Re: [PATCH 02/10] perf/x86: Improve HT workaround GP counter constraint

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Message-ID: <20150522132514.GC3644@twins.programming.kicks-ass.net>
Date:	Fri, 22 May 2015 15:25:14 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Vince Weaver <vincent.weaver@...ne.edu>,
	Jiri Olsa <jolsa@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 02/10] perf/x86: Improve HT workaround GP counter
 constraint

On Fri, May 22, 2015 at 06:05:49AM -0700, Stephane Eranian wrote:
> > I bet you tested the exclusive events earlier :-) Its one of the bugs,
> > the n_excl accounting is leaking up. Once !0 it stays !0.
> 
> So you're saying intel_put_excl_constraint() does not do the --n_excl?

No it does, but we call get_events_constraints() every time we do
x86_schedule_events(), and put_events_constraints() only on
x86_pmu_del(). This means we call get() much more than we put().

Therefore leak up.
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