Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758187Ab2EATEz (ORCPT ); Tue, 1 May 2012 15:04:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:5418 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755921Ab2EATEy (ORCPT ); Tue, 1 May 2012 15:04:54 -0400 From: Jeff Moyer To: Vivek Goyal Cc: Jens Axboe , Tejun Heo , Dave Jones , "linux-kernel\@vger.kernel.org" , Sasha Levin Subject: Re: [PATCH v3.4-rc5] block: iocontext->nr_tasks should be initialized to one References: <1335873936.16988.148.camel@lappy> <20120501161729.GV26595@google.com> <4FA0253F.4000302@fusionio.com> <20120501180906.GX26595@google.com> <4FA028EE.7020208@fusionio.com> <20120501183610.GD18239@redhat.com> <20120501185906.GE18239@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: Tue, 01 May 2012 15:04:49 -0400 In-Reply-To: <20120501185906.GE18239@redhat.com> (Vivek Goyal's message of "Tue, 1 May 2012 14:59:06 -0400") 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=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1797 Lines: 48 Vivek Goyal writes: > On Tue, May 01, 2012 at 02:48:41PM -0400, Jeff Moyer wrote: >> Vivek Goyal writes: >> >> > On Tue, May 01, 2012 at 02:31:07PM -0400, Jeff Moyer wrote: >> > >> > [..] >> >> > But as to actual users, I really don't know. I agree it's probably not >> >> > that widely used. If google still had that code search, we could get a >> >> > better idea :-) >> >> >> >> I know of one project: the venerable dump/restore utility uses CLONE_IO. >> > >> > I thought you wrote cooperating queue logic to fix dump as it was not >> > using CLONE_IO and IO from multiple threads was going in separate >> > queues. >> >> That's correct. I believe I sent the patch for dump before the kernel >> patch was accepted. Plus, it can't hurt, right? > > Ok, so now you have fixed dump to use CLONE_IO. > > So only other user of coop thing remaining potentially is qemu. I was No, that's not the *only* other potential user. ;-) I wouldn't be surprised if nfsd benefitted from the merging. I also wouldn't be surprised if other 3rd party apps did. Are you trying to make a case to get rid of the queue merging logic? > doing some qemu testing where threads were doing IO to nearby area > but no coop merging was taking place. So not sure in practice how well > does it work. Well, that sounds like it warrants further investigation. > Thought, that's irrlevant for this discussion. Thought of mentioning > this observation. If you can provide a reproducer, I'll be happy to take a look. Cheers, 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/