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From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>,
	K Prateek Nayak <kprateek.nayak@amd.com>,
	 Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	 Len Brown <lenb@kernel.org>,
	ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
	 Linux PM <linux-pm@vger.kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	 Thomas Gleixner <tglx@linutronix.de>,
	andi@lisas.de, Pu Wen <puwen@hygon.cn>,
	 Mario Limonciello <mario.limonciello@amd.com>,
	"Zhang, Rui" <rui.zhang@intel.com>,
	 "Guilherme G. Piccoli" <gpiccoli@igalia.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	ananth.narayan@amd.com,  gautham.shenoy@amd.com,
	Calvin Ong <calvin.ong@amd.com>,  Stable <stable@vger.kernel.org>,
	regressions@lists.linux.dev
Subject: Re: [PATCH] ACPI: processor_idle: Skip dummy wait for processors based on the Zen microarchitecture
Date: Thu, 22 Sep 2022 17:21:21 +0200	[thread overview]
Message-ID: <CAJZ5v0i9P-srVxrSPZOkXhKVCA2vEQqm5B4ZZifS=ivpwv+A-w@mail.gmail.com> (raw)
In-Reply-To: <YywaAcTdLSuDlRfl@hirez.programming.kicks-ass.net>

On Thu, Sep 22, 2022 at 10:17 AM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Wed, Sep 21, 2022 at 09:48:13PM +0200, Borislav Petkov wrote:
> > 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?
>
> I've no idea what they do, but Linux exclusively uses MWAIT on Intel as
> per intel_idle.c.

Well, it can be forced to use ACPI idle instead.

> MWAIT also cuts down on IPIs because it wakes from the TIF write.

Right.

  reply	other threads:[~2022-09-22 15:21 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-21  6:36 [PATCH] ACPI: processor_idle: Skip dummy wait for processors based on the Zen microarchitecture K Prateek Nayak
2022-09-21  8:47 ` Borislav Petkov
2022-09-21 10:39   ` K Prateek Nayak
2022-09-21 13:10     ` Borislav Petkov
2022-09-21 14:15 ` Dave Hansen
2022-09-21 19:51   ` Borislav Petkov
2022-09-21 19:55     ` Limonciello, Mario
2022-09-22  3:58     ` Ananth Narayan
2022-09-22  5:44   ` K Prateek Nayak
     [not found]   ` <20220923160106.9297-1-ermorton@ericmoronsm1mbp.amd.com>
2022-09-23 16:15     ` Ananth Narayan
2022-09-21 15:00 ` Peter Zijlstra
2022-09-21 19:48   ` Borislav Petkov
2022-09-22  8:17     ` Peter Zijlstra
2022-09-22 15:21       ` Rafael J. Wysocki [this message]
2022-09-22 15:36         ` Borislav Petkov
2022-09-22 15:53           ` Rafael J. Wysocki
2022-09-22 16:36             ` Dave Hansen
2022-09-22 16:44 ` Dave Hansen
2022-09-22 16:54   ` K Prateek Nayak
2022-09-22 17:01     ` Dave Hansen
2022-09-22 17:48       ` Limonciello, Mario
2022-09-22 18:17         ` Dave Hansen
2022-09-22 18:28           ` Limonciello, Mario
2022-09-23 11:47             ` Ananth Narayan
2022-09-22 19:42       ` Andreas Mohr
2022-09-22 20:10         ` Andreas Mohr
2022-09-22 21:21           ` Dave Hansen
2022-09-22 21:38             ` Limonciello, Mario
2022-09-23  7:42             ` Peter Zijlstra
2022-09-23  7:57             ` Peter Zijlstra

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