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From: Dave Hansen <dave.hansen@intel.com>
To: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>,
	Patryk Wlazlyn <patryk.wlazlyn@linux.intel.com>,
	x86@kernel.org
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
	rafael.j.wysocki@intel.com, len.brown@intel.com,
	dave.hansen@linux.intel.com
Subject: Re: [PATCH v2 2/3] x86/smp: Allow forcing the mwait hint for play dead loop
Date: Wed, 6 Nov 2024 06:46:18 -0800	[thread overview]
Message-ID: <7c08ebf7-69dd-44c1-b43e-fb9b50704dd6@intel.com> (raw)
In-Reply-To: <9272406507bca4eb284cd75759d8d9479b937da9.camel@linux.intel.com>

On 11/6/24 00:14, Artem Bityutskiy wrote:
> The non-architectural part of it is basically this.
> 
> The algorithm assumes that in the sub-state part of the mwait hint (4 least
> significant bits) always starts with 0 and then next sub-state is always 1, and
> there are no gaps. This is not documented in Intel SDM. This happens to work on
> majority of Intel platforms, but this is not architectural.

I wouldn't call that a "non-architectural algorithm".  It's a bug, plain
and simple.

  reply	other threads:[~2024-11-06 14:46 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-29 10:15 [PATCH v2 0/3] SRF: Fix offline CPU preventing pc6 entry Patryk Wlazlyn
2024-10-29 10:15 ` [PATCH v2 1/3] x86/smp: Move mwait hint computation out of mwait_play_dead Patryk Wlazlyn
2024-10-29 10:15 ` [PATCH v2 2/3] x86/smp: Allow forcing the mwait hint for play dead loop Patryk Wlazlyn
2024-10-29 18:30   ` Dave Hansen
2024-10-30  9:58     ` Artem Bityutskiy
2024-10-30 19:32       ` Dave Hansen
2024-10-30 19:53         ` Rafael J. Wysocki
2024-10-30 20:11           ` Dave Hansen
2024-10-30 20:14             ` Rafael J. Wysocki
2024-11-06  8:14         ` Artem Bityutskiy
2024-11-06 14:46           ` Dave Hansen [this message]
2024-10-30 13:33     ` Patryk Wlazlyn
2024-10-30 22:55       ` Dave Hansen
2024-10-29 10:15 ` [PATCH v2 3/3] intel_idle: Identify the deepest cstate for SRF Patryk Wlazlyn

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