From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755187Ab0IBNt2 (ORCPT ); Thu, 2 Sep 2010 09:49:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41006 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752340Ab0IBNt1 (ORCPT ); Thu, 2 Sep 2010 09:49:27 -0400 From: Jeff Moyer To: Doug Neal Cc: linux-kernel@vger.kernel.org Subject: Re: I/O scheduler deadlocks on Xen virtual block devices References: X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Thu, 02 Sep 2010 09:47:02 -0400 In-Reply-To: (Doug Neal's message of "Thu, 2 Sep 2010 09:34:59 +0100") Message-ID: User-Agent: Gnus/5.110011 (No Gnus v0.11) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Doug Neal writes: >> >> Did you try these different I/O schedulers in the domU or on the dom0? >> Does switching I/O schedulers in either place make the problem go away >> when it happens? >> > > In the domU, and the bug was present in all cases. The dom0 was using > cfq. I'll run the tests again using each scheduler in the dom0 with > domU set to noop and report back. While I think this is an interesting test, you need only test one I/O scheduler in the dom0. Also, I think you misunderstood the second question. I'd like to know if switching I/O schedulers while the system is in this bad state helps get I/O going again. Cheers, Jeff