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Subject: Re: [PATCH 1/5] perf: Provide a proper stop action for software
 events
From: Peter Zijlstra <peterz@infradead.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>,
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Date: Thu, 10 Jun 2010 18:38:34 +0200
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On Thu, 2010-06-10 at 18:29 +0200, Frederic Weisbecker wrote:

> Imagine you have several software and hardware events running on the
> same cpu. Each time you reset this period for a software event, you do
> a hw_pmu_disable() / hw_pmu_enable(), which writes/read the hardware
> register for each hardware events, amongst other wasteful things.

hw_perf_disable/enable() are on their way out. They should be replaced
with a struct pmu callback. We must remove all these weak functions if
we want to support multiple pmus.