linux-kernel - Re: [PATCH 3/3] perf/x86/rapl: Fix psys-energy event on Intel SPR platform

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Date:   Fri, 05 Feb 2021 00:04:25 +0800
From:   Zhang Rui <rui.zhang@...el.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     "mingo@...hat.com" <mingo@...hat.com>,
        "acme@...nel.org" <acme@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "alexander.shishkin@...ux.intel.com" 
        <alexander.shishkin@...ux.intel.com>,
        "jolsa@...hat.com" <jolsa@...hat.com>,
        "namhyung@...nel.org" <namhyung@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "kan.liang@...ux.intel.com" <kan.liang@...ux.intel.com>,
        "ak@...ux.intel.com" <ak@...ux.intel.com>
Subject: Re: [PATCH 3/3] perf/x86/rapl: Fix psys-energy event on Intel SPR
 platform

Hi, Peter,

On Wed, 2021-02-03 at 15:47 +0100, Peter Zijlstra wrote:
> FWIW, your email is malformed, please wrap at 78 chars.
> 
> On Mon, Jan 25, 2021 at 06:11:14AM +0000, Zhang, Rui wrote:
> > In short, the current code does not allow RAPL energy counter to
> > return 0. And all the work I do is to allow Psys energy counter to
> > return 0.
> 
> Ok.
> 
> > In this way, the Psys event is "valid" on all CPUs, so we don't
> > need
> > to handle the master thing.
> 
> So RAPL is mapped to DIEs, and IIRC we can have multiple DIEs per
> Package. But the master thing is a Package.
> 
> Is this all moot because SPR has one DIE per Package?

Oh, right.
This is not a problem on SPR because it is a single-die
platform.

>  Because if it
> would have more, there's be more interesting problems I suppose.

Agreed.

thanks,
rui