Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 26 Nov 2002 10:18:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 26 Nov 2002 10:18:39 -0500 Received: from thunk.org ([140.239.227.29]:52689 "EHLO thunker.thunk.org") by vger.kernel.org with ESMTP id ; Tue, 26 Nov 2002 10:18:38 -0500 Date: Tue, 26 Nov 2002 10:22:38 -0500 From: "Theodore Ts'o" To: Andrew Morton Cc: Manish Lachwani , linux-kernel@vger.kernel.org Subject: Re: 2.4.17 SMP hangs .. Message-ID: <20021126152238.GA4408@think.thunk.org> Mail-Followup-To: Theodore Ts'o , Andrew Morton , Manish Lachwani , linux-kernel@vger.kernel.org References: <233C89823A37714D95B1A891DE3BCE5202AB1975@xch-a.win.zambeel.com> <3DDC7746.200ACDE2@digeo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3DDC7746.200ACDE2@digeo.com> User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1582 Lines: 37 On Wed, Nov 20, 2002 at 10:03:50PM -0800, Andrew Morton wrote: > Manish Lachwani wrote: > > > > I am seeing system hangs with 2.4.17 SMP kernel when doing mke2fs accros 12 > > drives in parallel. However, the hangs only occur when the I/O rate from > > vmstat is high: > > > > Quite possibly it has not hung. You just need to wait half an > hour or so. > > The algorithm isn't very good. [Catching up lkml mail after the IETF meeting....] Try setting the environment variable "MKE2FS_SYNC" to a value such as 10. This will cause mke2fs to force a sync after writing out every 10 block groups worth of inode tables. If this fixes the problem, then it means that the kernel isn't handling write throttling correctly, and the system is thrashing itself to death. Write thottleing is one of these kernel bugs which gets fixed and broken in the kernel multiple times. I've considered making MKE2FS_SYNC the default, but I haven't, mainly because current behaviour is a great way of pointing out this write throttling bugs in the VM. (Stephen has fixed this bug multiple times over the years, and he suggested that having a good test case for noticing when someone has broken write throttling would be a Good Thing --- and it seems to get broken fairly often, as people try to make improvements to the VM layer.....) - Ted - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/