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

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Message-ID: <48885DDC.9010003@fujitsu-siemens.com>
Date:	Thu, 24 Jul 2008 12:47:56 +0200
From:	Martin Wilck <martin.wilck@...itsu-siemens.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>
CC:	"Wichert, Gerhard" <Gerhard.Wichert@...itsu-siemens.com>
Subject: [PATCH] x86 (64): make calibrate_APIC_clock() smp-safe

Hi Thomas and Peter, hi everyone,

Asynchrounous events (e.g.SMIs) which occur during the APIC timer 
calibration can cause timer miscalibrations, sometimes by large amounts.

This patch fixes this by two separate measures:
   a) make sure that no significant interruption occurs between APIC and
      TSC reads
   b) make sure that the measurement loop isn't significantly longer
      than originally intended.

I am sorry, due to a misconfiguration of our SMTP server I need to send 
the patch as attachment.

Martin

-- 
Martin Wilck
PRIMERGY System Software Engineer
FSC IP ESP DEV 6

Fujitsu Siemens Computers GmbH
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View attachment "calibrate_APIC_clock-1.diff" of type "text/x-patch" (2383 bytes)