From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756188AbXHUJfH (ORCPT ); Tue, 21 Aug 2007 05:35:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756562AbXHUJeb (ORCPT ); Tue, 21 Aug 2007 05:34:31 -0400 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:55088 "EHLO amd.ucw.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754453AbXHUJeK (ORCPT ); Tue, 21 Aug 2007 05:34:10 -0400 Date: Tue, 21 Aug 2007 09:42:01 +0200 From: Pavel Machek To: Peter Zijlstra Cc: "Ed L. Cashin" , kernel list , ak@suse.de, Netdev list Subject: Re: ATA over ethernet swapping Message-ID: <20070821074201.GC7258@elf.ucw.cz> References: <20070731135831.GA4604@elf.ucw.cz> <20070731150324.GE3206@coraid.com> <20070731152924.GM2087@elf.ucw.cz> <20070731162140.GI3206@coraid.com> <20070731222742.GR2087@elf.ucw.cz> <1185959909.12034.38.camel@twins> <20070809101105.GA7581@elf.ucw.cz> <1186991157.20108.47.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1186991157.20108.47.camel@twins> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.11+cvs20060126 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > But I'm able to compile kernel (-j 10) on 128MB machine, and I tried > > cat /dev/zero | grep foo to exhaust memory... and could not reproduce > > the deadlock. Should I pingflood? Tweak down ammount of atomic memory > > avaialable to make deadlocks easier to reproduce? > > I usually test swap over NFS in the following manner, I setup a regular > inet service on the machine (apache or a bunch of ncat sockets piping to > files or something) and run a heavy workload on the machine (128M): > 2*64M file backed thrashers and 2*64M anonymous thrashers. Then I start > clients for the regular inet service, wait for a bit, and shut down the > NFS server. > > This makes the machine grind to a halt, I then restart the NFS server, > wait for it to reconnect and the client to come alive again. > > Without the last few swap-over-NFS patches this last bit - getting back > out of that situation - never happens. > > The basic idea is to make connectivity to the machine where swap traffic > goes very hard (pull a cable, cleanly shut down the server) and to keep > other network traffic pounding the machine. Hmm, I could not get swap-over-ata-over-ethernet to break. Maybe I should not have local / filesystem, because it allows kernel to get rid of some memory pressure by dropping clean pages? Plus I guess ata-over-ethernet has some significant advantages, as it works over ethernet directly, not over IP. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html