linux-kernel - Re: [PATCH 1/2] perf/x86/rapl: Add support for Intel Meteor Lake

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Message-ID: <Y7g1FCY4Y+hY26aC@zn.tnic>
Date:   Fri, 6 Jan 2023 15:49:56 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Zhang, Rui" <rui.zhang@...el.com>
Cc:     "Hansen, Dave" <dave.hansen@...el.com>,
        "ak@...ux.intel.com" <ak@...ux.intel.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "linux-perf-users@...r.kernel.org" <linux-perf-users@...r.kernel.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "kan.liang@...ux.intel.com" <kan.liang@...ux.intel.com>,
        "Bityutskiy, Artem" <artem.bityutskiy@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] perf/x86/rapl: Add support for Intel Meteor Lake

On Fri, Jan 06, 2023 at 02:38:10PM +0000, Zhang, Rui wrote:
> And then set the feature flags based on this, and make the drivers test
> the feature flags.

That would be the purpose of synthetic flags.

> The goal of this is to do model list update in one place instead of 4
> or more different drivers when a new model comes.

Do you really have to update 4 different places each time?

As said before, you have to do the model matching *somewhere*. If you have to do
model matching in a lot of drivers - and it looks like you do - judging by

$ git grep X86_MATCH_INTEL_FAM6

output, then doing the matching once in cpu/intel.c and setting a synthetic flag
does make sense because all that matching code will disappear from all the
drivers but be concentrated in one place.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette