Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754868AbYCKNKr (ORCPT ); Tue, 11 Mar 2008 09:10:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751252AbYCKNKj (ORCPT ); Tue, 11 Mar 2008 09:10:39 -0400 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:34181 "EHLO gprs189-60.eurotel.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750923AbYCKNKi (ORCPT ); Tue, 11 Mar 2008 09:10:38 -0400 Date: Tue, 11 Mar 2008 11:09:04 +0100 From: Pavel Machek To: Paul Clements Cc: Andrew Morton , linux-kernel@vger.kernel.org, nbd-general@lists.sourceforge.net, Laurent Vivier Subject: Re: [PATCH 1/1] NBD: allow nbd to be used locally Message-ID: <20080311100904.GA807@elf.ucw.cz> References: <47D468F0.8000506@steeleye.com> <20080310102917.GA27751@elf.ucw.cz> <47D56F4A.5070208@steeleye.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <47D56F4A.5070208@steeleye.com> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1233 Lines: 28 On Mon 2008-03-10 13:26:34, Paul Clements wrote: > Pavel Machek wrote: > >>> This patch allows a Network Block Device to be mounted locally >>> (nbd-client to nbd-server over 127.0.0.1). >>> >>> It creates a kthread to avoid the deadlock described in NBD tools >>> documentation. So, if nbd-client hangs waiting for pages, the kblockd >>> thread can continue its work and free pages. >> >> What happens if your new kthread blocks on memory allocation? > > Well, we expect that. The reason for the new thread is so that it hangs, > rather than kblockd hanging (which on a UP system brings all I/O to a > halt). As long as kblockd can continue making progress, we eventually free > up memory and then NBD can finish its requests, too. ...unless all the memory is in dirty buffers for nbd, and nbd server is swapped out or something? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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/