linux-kernel - Re: [PATCH v1 0/2] x86/smp: Fix power regression introduced by commit 96040f7273e2

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Message-ID: <CAJZ5v0hw1910Gsb57POVhax1hAbEGHa7xksr_FygNd_JL-oeOA@mail.gmail.com>
Date: Thu, 29 May 2025 11:38:05 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, "Rafael J. Wysocki" <rjw@...ysocki.net>, 
	x86 Maintainers <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>, 
	Linux PM <linux-pm@...r.kernel.org>, Len Brown <lenb@...nel.org>, 
	Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...e.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, 
	Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>, 
	"Gautham R. Shenoy" <gautham.shenoy@....com>, Ingo Molnar <mingo@...hat.com>, 
	Todd Brandt <todd.e.brandt@...ux.intel.com>
Subject: Re: [PATCH v1 0/2] x86/smp: Fix power regression introduced by commit 96040f7273e2

On Thu, May 29, 2025 at 10:54 AM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Wed, May 28, 2025 at 07:09:21PM +0200, Rafael J. Wysocki wrote:
>
> > And I object to leaving a user-visible regression behind.
>
> So we go fix it differently.
>
> Why can't we initialize cpuidle before SMP bringup?

First off, I'm not sure if all of the requisite things are ready then
(sysfs etc.).

We may end up doing this eventually, but it may not be straightforward.

More importantly, this is not a change for 6.15.y (y > 0).