From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753582Ab2DBQ6x (ORCPT ); Mon, 2 Apr 2012 12:58:53 -0400 Received: from tex.lwn.net ([70.33.254.29]:46271 "EHLO vena.lwn.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751731Ab2DBQ6w (ORCPT ); Mon, 2 Apr 2012 12:58:52 -0400 Date: Mon, 2 Apr 2012 10:58:50 -0600 From: Jonathan Corbet To: Michael Tokarev Cc: Kernel Mailing List Subject: Re: dramatic I/O slowdown after upgrading 2.6.32->3.0 Message-ID: <20120402105850.270fe7f2@lwn.net> In-Reply-To: <4F75E46E.2000503@msgid.tls.msk.ru> References: <4F75E46E.2000503@msgid.tls.msk.ru> Organization: LWN.net X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.10; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 30 Mar 2012 20:50:54 +0400 Michael Tokarev wrote: > I'm observing a dramatic slowdown of several hosts after upgrading > from 2.6.32.y to 3.0.x i686 kernels (in both cases from kernel.org, > on both cases the last version is relatively latest). > > On 2.6.32 everything is fast. On 3.0 the same operations which goes > instantly takes ages to complete. [...] > What's the way to debug this issue? There is a huge gap between those two kernels, so nobody is going to have much luck guessing about what has changed. A good first step might be to do a binary search among the intermediate kernel releases to figure out which one slowed things down for you. jon