linux-kernel - Re: Lossy interrupts on x86

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Date:	Thu, 13 Sep 2007 09:40:44 -0400
From:	Chris Snook <csnook@...hat.com>
To:	Jesse Barnes <jbarnes@...tuousgeek.org>
CC:	Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org
Subject: Re: Lossy interrupts on x86_64

Jesse Barnes wrote:
> I just narrowed down a weird problem where I was losing more than 50% of 
> my vblank interrupts to what seems to be the hires timers patch.  Stock 
> 2.6.23-rc5 works fine, but the latest (171) kernel from rawhide drops 
> most of my interrupts unless I also have another interrupt source 
> running (e.g. if I hold down a key or move the mouse I get the expected 
> number of vblank interrupts, otherwise I get between 3 and 30 instead 
> of the expected 60 per second).
> 
> Any ideas?  It seems like it might be bad APIC programming, but I 
> haven't gone through those mods to look for suspects...

What happens if you boot with 'noapic' or 'pci=nomsi'?  Please post dmesg as 
well so we can see how the kernel is initializing the relevant hardware.

	-- Chris
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