linux-kernel - Re: [PATCH 1/3] perf: use hrtimer for event multiplexing

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Message-ID: <CABPqkBSQwduG2bwz0DYP1HPf+4_SQOMhxTBSnKSX-CmATBa93A@mail.gmail.com>
Date:	Fri, 7 Sep 2012 21:10:20 +0200
From:	Stephane Eranian <eranian@...gle.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu, ak@...ux.intel.com,
	zheng.z.yan@...el.com, robert.richter@....com
Subject: Re: [PATCH 1/3] perf: use hrtimer for event multiplexing

On Fri, Sep 7, 2012 at 9:08 PM, Peter Zijlstra <peterz@...radead.org> wrote:
> On Fri, 2012-09-07 at 19:03 +0200, Stephane Eranian wrote:
>> I think having different intervals would be a good thing, especially for uncore.
>> But now, I am wondering how this could work without too much overhead.
>> Looks like you're suggesting arming multiple hrtimers if multiple PMU are
>> overcommitted. Is that right?
>
> Right, we shoulnd't have too many PMUs anyway, let alone over committed
> ones, so a timer per cpu per pmu should be fine.
>
>>  As opposed to having a PMU multiplier off of a
>> single per-cpu hrtimer.

That's true. I started modifying my code to implement your suggestion.
We'll see how it goes. Then we would have to export that mux interval
via sysfs for each PMU.
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