From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S970524AbXILRGu (ORCPT ); Wed, 12 Sep 2007 13:06:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S970457AbXILRGj (ORCPT ); Wed, 12 Sep 2007 13:06:39 -0400 Received: from www.osadl.org ([213.239.205.134]:36436 "EHLO mail.tglx.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S970451AbXILRGi (ORCPT ); Wed, 12 Sep 2007 13:06:38 -0400 Subject: Re: Lossy interrupts on x86_64 From: Thomas Gleixner To: Jesse Barnes Cc: Randy Dunlap , linux-kernel@vger.kernel.org In-Reply-To: <200709120929.52217.jbarnes@virtuousgeek.org> References: <200709120833.15980.jbarnes@virtuousgeek.org> <20070912090151.97c9a78e.randy.dunlap@oracle.com> <200709120929.52217.jbarnes@virtuousgeek.org> Content-Type: text/plain Date: Wed, 12 Sep 2007 19:06:35 +0200 Message-Id: <1189616795.4302.1.camel@chaos> Mime-Version: 1.0 X-Mailer: Evolution 2.11.92 (2.11.92-1.fc8) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2007-09-12 at 09:29 -0700, Jesse Barnes wrote: > On Wednesday, September 12, 2007, Randy Dunlap wrote: > > 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. That's a suspend / resume problem which we are hunting. > > but you said "any ideas" > > Yeah, there's NO_HZ in the rawhide kernel too, but I'm getting timer > ticks normally afaict, it's just vblank interrupts that get lost... Jesse, does it make any difference when you boot the box with: nohz=off on the kernel command line ? tglx