From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753533Ab0IQJf0 (ORCPT ); Fri, 17 Sep 2010 05:35:26 -0400 Received: from claranet-outbound-smtp00.uk.clara.net ([195.8.89.33]:45249 "EHLO claranet-outbound-smtp00.uk.clara.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752215Ab0IQJfV convert rfc822-to-8bit (ORCPT ); Fri, 17 Sep 2010 05:35:21 -0400 X-Greylist: delayed 1981 seconds by postgrey-1.27 at vger.kernel.org; Fri, 17 Sep 2010 05:35:21 EDT From: Simon Farnsworth To: intel-gfx@lists.freedesktop.org Subject: Re: [Intel-gfx] Interrupt latency on some 945GM platforms Date: Fri, 17 Sep 2010 10:02:08 +0100 User-Agent: KMail/1.13.3 (Linux/2.6.34.1-100.tv.pf.fc13.x86_64; KDE/4.4.4; x86_64; ; ) Cc: Vasily Khoruzhick , Sitsofe Wheeler , Venkatesh Pallipadi , Thomas Gleixner , linux-kernel@vger.kernel.org, Jesse Barnes References: <201009132336.17310.anarsoul@gmail.com> <20100914224111.GA14467@sucs.org> <201009161803.10531.anarsoul@gmail.com> In-Reply-To: <201009161803.10531.anarsoul@gmail.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Message-Id: <201009171002.09187.simon.farnsworth@onelan.co.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 16 September 2010, Vasily Khoruzhick wrote: > В сообщении от 15 of September 2010 01:41:11 автор Sitsofe Wheeler написал: > > > > processor.max_cstate=2 > > > > > > Nope, it doesn't work with max_cstate=2 > > > > Perhaps intel_idle is being used? Any mention of it in dmesg? > > Sitsofe, maybe you misunderstood me, I mean with max_cstate=1 graphics is > smooth, with higher values (i.e. max_cstate=2) graphics is jerky. > > Btw, Jesse, any comments/solutions/workarounds except one with > processor.max_cstate=1 in kernel commandline? Should I file a bug on fdo > bugzilla? This looks like a problem I've seen on some hardware. My workaround has been to use the pm_qos /dev/cpu_dma_latency interface to request a maximum latency of 1ms (value chosen as definitely small enough - a larger value may be better, but I don't care about power saving at runtime on my kit). If it's happening on other kit, perhaps the i915 driver should make a suitable pm_qos request itself. Jesse, can you comment? -- Simon Farnsworth Software Engineer ONELAN Limited http://www.onelan.com/