linux-kernel - Re: [PATCH] ACPI: processor_idle: Skip dummy wait for processors based on the Zen microarchitecture

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Message-ID: <YytqfVUCWfv0XyZO@zn.tnic>
Date:   Wed, 21 Sep 2022 21:48:13 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     K Prateek Nayak <kprateek.nayak@....com>,
        linux-kernel@...r.kernel.org, rafael@...nel.org, lenb@...nel.org,
        linux-acpi@...r.kernel.org, linux-pm@...r.kernel.org,
        dave.hansen@...ux.intel.com, tglx@...utronix.de, andi@...as.de,
        puwen@...on.cn, mario.limonciello@....com, rui.zhang@...el.com,
        gpiccoli@...lia.com, daniel.lezcano@...aro.org,
        ananth.narayan@....com, gautham.shenoy@....com,
        Calvin Ong <calvin.ong@....com>, stable@...r.kernel.org,
        regressions@...ts.linux.dev
Subject: Re: [PATCH] ACPI: processor_idle: Skip dummy wait for processors
 based on the Zen microarchitecture

On Wed, Sep 21, 2022 at 05:00:35PM +0200, Peter Zijlstra wrote:
> On Wed, Sep 21, 2022 at 12:06:38PM +0530, K Prateek Nayak wrote:
> > Processors based on the Zen microarchitecture support IOPORT based deeper
> > C-states. 
> 
> I've just gotta ask; why the heck are you using IO port based idle
> states in 2022 ?!?! You have have MWAIT, right?

They have both. And both is Intel technology. And as I'm sure you
know AMD can't do their own thing - they kinda have to follow Intel.
Unfortunately.

Are you saying modern Intel chipsets don't do IO-based C-states anymore?

-- 
Regards/Gruss,
    Boris.

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