Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753173Ab2JCObA (ORCPT ); Wed, 3 Oct 2012 10:31:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:7976 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752167Ab2JCOa6 convert rfc822-to-8bit (ORCPT ); Wed, 3 Oct 2012 10:30:58 -0400 From: Jeff Moyer To: Dave Chinner Cc: =?utf-8?B?THVrw6HFoQ==?= Czerner , Jens Axboe , linux-kernel@vger.kernel.org Subject: Re: [PATCH] loop: Limit the number of requests in the bio list References: <1348767205-17230-1-git-send-email-lczerner@redhat.com> <20121002195934.GA2657@devil.redhat.com> 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: Wed, 03 Oct 2012 10:30:54 -0400 In-Reply-To: <20121002195934.GA2657@devil.redhat.com> (Dave Chinner's message of "Wed, 3 Oct 2012 05:59:34 +1000") 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=utf-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1906 Lines: 40 Dave Chinner writes: > On Tue, Oct 02, 2012 at 10:52:05AM +0200, Lukáš Czerner wrote: >> On Mon, 1 Oct 2012, Jeff Moyer wrote: >> > Date: Mon, 01 Oct 2012 12:52:19 -0400 >> > From: Jeff Moyer >> > To: Lukas Czerner >> > Cc: Jens Axboe , linux-kernel@vger.kernel.org, >> > Dave Chinner >> > Subject: Re: [PATCH] loop: Limit the number of requests in the bio list >> > >> > Lukas Czerner writes: >> > >> > > Currently there is not limitation of number of requests in the loop bio >> > > list. This can lead into some nasty situations when the caller spawns >> > > tons of bio requests taking huge amount of memory. This is even more >> > > obvious with discard where blkdev_issue_discard() will submit all bios >> > > for the range and wait for them to finish afterwards. On really big loop >> > > devices this can lead to OOM situation as reported by Dave Chinner. >> > > >> > > With this patch we will wait in loop_make_request() if the number of >> > > bios in the loop bio list would exceed 'nr_requests' number of requests. >> > > We'll wake up the process as we process the bios form the list. >> > >> > I think you might want to do something similar to what is done for >> > request_queues by implementing a congestion on and off threshold. As >> > Jens writes in this commit (predating the conversion to git): >> >> Right, I've had the same idea. However my first proof-of-concept >> worked quite well without this and my simple performance testing did >> not show any regression. Did you look at system time? -Jeff -- 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/