From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932975Ab1BYU1y (ORCPT ); Fri, 25 Feb 2011 15:27:54 -0500 Received: from adelie.canonical.com ([91.189.90.139]:37587 "EHLO adelie.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932139Ab1BYU1w (ORCPT ); Fri, 25 Feb 2011 15:27:52 -0500 Date: Fri, 25 Feb 2011 14:27:48 -0600 From: Seth Forshee To: Steven Rostedt Cc: Linux Kernel Mailing List , Ingo Molnar , Thomas Gleixner Subject: Re: Performance/resume issues on Toshiba NB305 Message-ID: <20110225202748.GB24686@thinkpad-t410> Mail-Followup-To: Steven Rostedt , Linux Kernel Mailing List , Ingo Molnar , Thomas Gleixner References: <20110225164239.GA24686@thinkpad-t410> <20110225201747.GB23161@home.goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110225201747.GB23161@home.goodmis.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 25, 2011 at 03:17:47PM -0500, Steven Rostedt wrote: > Would be helpful to Cc the people that may help you. > > > On Fri, Feb 25, 2011 at 10:42:39AM -0600, Seth Forshee wrote: > > I've been looking into a couple of problems with this machine that have > > me a bit stumped at the moment. The two problems may or may not be > > related, so I'm including details about both issues below. If anyone has > > any ideas, I'd love to hear them. Note that these are not recent > > regressions; they've been around since at least 2.6.32. > > > > The CPU in this machine is an Atom N450. > > > > When booted normally the performance on this machine is very poor, but > > when booted with any of nohz=off, nolapic, or nohpet it improves > > significantly. The performance also improves if I use the patch below to > > force the hpet to remain in periodic mode (with hpet=periodic on the > > command line). > > > > One other thing I noticed when I had added some logging related to hpet > > rearming is 3-5 second periods of no log activity occurring fairly > > frequently, whereas such inactive periods are infrequent when > > performance is good and are also infrequent on another machine with very > > similar hardware and no performance issues. > > > > The machine also hangs for 5 minutes during resume, unless booted with > > both nohz=off and highres=off, or with hpet=periodic using the patch > > below. I've traced this down to hanging in an SMI handler during the > > ACPI _WAK method execution. The 5 minutes corresponds to how long it > > takes for the low 32 bits of the hpet to wrap in this machine, and since > > the options that eliminate the hang result in the hpet being in periodic > > mode during _WAK method execution I suspect that the SMI handler is > > hanging until a timer interrupt happens. > > > > One possible explanation here is that the performance problems are also > > related to hangs in SMI handlers until there's a timer interrupt, > > although I don't know how that explains why some of the command line > > options eliminate the performance issues. > > Sounds like a buggy BIOS to me. Is there upgrades available for this > box? It does sound like a buggy BIOS. I've already flashed the latest BIOS though, so no luck there.