linux-kernel - Re: [RFC] Sharing PMU counters across compatible events

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Message-ID: <20171213161519.GU3919388@devbig577.frc2.facebook.com>
Date:   Wed, 13 Dec 2017 08:15:19 -0800
From:   Tejun Heo <tj@...nel.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org, kernel-team@...com
Subject: Re: [RFC] Sharing PMU counters across compatible events

Hello, Jiri.

On Wed, Dec 13, 2017 at 11:18:07AM +0100, Jiri Olsa wrote:
> so I can see this to be useful for HW conters only, because
> of limited number of regs
> 
> as for the higher level on which this could be implemented I
> see some pitfals with event rotations as Peter mentioned and
> task/cpu contexts scheduling.. while the hw-level implementation
> seems pretty straight forward

Heh, yeah, maybe.  

> I'll test the code and let's see ;-)

Thanks.  I'll think more about it and see whether this can be evolved
into something useable.

Thanks.

-- 
tejun