linux-kernel - Re: [PATCH] x86 (64): make calibrate_APIC

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Message-ID: <488889B6.9070707@fujitsu-siemens.com>
Date:	Thu, 24 Jul 2008 15:55:02 +0200
From:	Martin Wilck <martin.wilck@...itsu-siemens.com>
To:	Cyrill Gorcunov <gorcunov@...il.com>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Wichert, Gerhard" <Gerhard.Wichert@...itsu-siemens.com>,
	"Maciej W. Rozycki" <macro@...ux-mips.org>
Subject: Re: [PATCH] x86 (64): make calibrate_APIC_clock() SMI-safe

Cyrill Gorcunov wrote:

> yes, it will issue some effects but it's better then stuck there.
> More over in 'case of SMI flood with current patch you don't get
> error message printed i think so you better add max iteration
> counter so user will see on console (or whatever) that he is got
> problems.
>                 - Cyrill -

I disagree. If you have a system that generates SMIs in this extreme 
frequency, you're better off stuck than running on such an unstable 
system. The user _will_ see messages on the console if this happens. 
Note that apparently there are few people who have trouble with this. We 
did see problems, but never had more than 1 SMI disturbing the 
calibration procedure.

Anyway, here is another patch that defines max iteration counts. I 
haven't added a "Signed-off:" line, because I prefer the original version.

Martin

-- 
Martin Wilck
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FSC IP ESP DEV 6

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View attachment "calibrate_APIC_clock-2.diff" of type "text/x-patch" (2341 bytes)