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From: Borislav Petkov <bp@alien8.de>
To: Dave Hansen <dave.hansen@intel.com>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>,
	linux-kernel@vger.kernel.org, rafael@kernel.org, lenb@kernel.org,
	linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org,
	dave.hansen@linux.intel.com, tglx@linutronix.de, andi@lisas.de,
	puwen@hygon.cn, mario.limonciello@amd.com, peterz@infradead.org,
	rui.zhang@intel.com, gpiccoli@igalia.com,
	daniel.lezcano@linaro.org, ananth.narayan@amd.com,
	gautham.shenoy@amd.com, Calvin Ong <calvin.ong@amd.com>,
	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: Wed, 21 Sep 2022 21:51:51 +0200	[thread overview]
Message-ID: <YytrV2UMah8555+s@zn.tnic> (raw)
In-Reply-To: <2b6143b6-9db4-05bc-1e8d-c5d129126f99@intel.com>

On Wed, Sep 21, 2022 at 07:15:07AM -0700, Dave Hansen wrote:
> In the end, the delay is because of buggy, circa 2006 chipsets?  So, we
> use a CPU vendor specific check to approximate that the chipset is
> recent and not affected by the bug?  If so, is there no better way to
> check for a newer chipset than this?

So I did some git archeology but that particular addition is in some
conglomerate, glued-together patch from 2007 which added the cpuidle
tree:

commit 4f86d3a8e297205780cca027e974fd5f81064780
Author: Len Brown <len.brown@intel.com>
Date:   Wed Oct 3 18:58:00 2007 -0400

    cpuidle: consolidate 2.6.22 cpuidle branch into one patch


so the most precise check here should be to limit that dummy read to
that Intel chipset which needed it. Damned if I knew how to figure out
which...

-- 
Regards/Gruss,
    Boris.

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

  reply	other threads:[~2022-09-21 19:51 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 [this message]
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
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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