Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757492Ab2EAS7N (ORCPT ); Tue, 1 May 2012 14:59:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45908 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756160Ab2EAS7K (ORCPT ); Tue, 1 May 2012 14:59:10 -0400 Date: Tue, 1 May 2012 14:59:06 -0400 From: Vivek Goyal To: Jeff Moyer 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 Message-ID: <20120501185906.GE18239@redhat.com> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1351 Lines: 34 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 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. Thought, that's irrlevant for this discussion. Thought of mentioning this observation. Thanks Vivek -- 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/