linux-kernel - Re: Lossy interrupts on x86

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Message-Id: <20070912090151.97c9a78e.randy.dunlap@oracle.com>
Date:	Wed, 12 Sep 2007 09:01:51 -0700
From:	Randy Dunlap <randy.dunlap@...cle.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

On Wed, 12 Sep 2007 08:33:15 -0700 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...

Also tickless?  (NO_HZ ?)

I think I've seen some emails about tickless and keystrokes being
needed to cause interrupts... but I'm not postive about it.

but you said "any ideas"

---
~Randy
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