linux-kernel - Re: [RFC PATCH 2/4] cpufreq: acpi-cpufreq: Add processor to the ignore PSD override list

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Message-ID: <20201214124023.GA25916@zn.tnic>
Date:   Mon, 14 Dec 2020 13:40:23 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Punit Agrawal <punitagrawal@...il.com>
Cc:     Wei Huang <whuang2@....com>, rjw@...ysocki.net, wei.huang2@....com,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        x86@...nel.org
Subject: Re: [RFC PATCH 2/4] cpufreq: acpi-cpufreq: Add processor to the
 ignore PSD override list

On Sat, Dec 12, 2020 at 08:36:48AM +0900, Punit Agrawal wrote:
> To me it suggests, that there are likely more systems from the family
> that show the characteristic described below.

Until we find a *single* system with a broken BIOS which has those
objects kaputt and then this heuristic would need an exception.

VS the clear statement from AMD that from zen3 onwards, all BIOS will be
tested. I hope they boot Linux at least before they ship.

> In all these systems, the override causes this topology information to
> be ignored - treating each core to be a separate domain. The proposed
> patch removes the override so that _PSD is taken into account.

You're still not answering my question: what does the coupling of the
SMT threads bring on those systems? Power savings? Perf improvement?
Anything palpable or measurable?

Thx.

-- 
Regards/Gruss,
    Boris.

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