From: Jeff Moyer Subject: Re: [RFC] ext4: Don't send extra barrier during fsync if there are no dirty pages. Date: Thu, 05 Aug 2010 15:13:44 -0400 Message-ID: References: <20100429235102.GC15607@tux1.beaverton.ibm.com> <1272934667.2544.3.camel@mingming-laptop> <4BE02C45.6010608@redhat.com> <20100504154553.GA22777@infradead.org> <20100630124832.GA1333@thunk.org> <4C5818A1.9070102@redhat.com> <20100804233206.GA2901@thunk.org> <4C5A1FDC.3010700@redhat.com> <20100805161745.GG2901@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , Christoph Hellwig , Ric Wheeler , Mingming Cao , djwong@us.ibm.com, linux-ext4 , linux-kernel , Keith Mannthey , Mingming Cao To: "Ted Ts'o" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:3132 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758831Ab0HETNw (ORCPT ); Thu, 5 Aug 2010 15:13:52 -0400 In-Reply-To: <20100805161745.GG2901@thunk.org> (Ted Ts'o's message of "Thu, 5 Aug 2010 12:17:45 -0400") Sender: linux-ext4-owner@vger.kernel.org List-ID: "Ted Ts'o" writes: > On Thu, Aug 05, 2010 at 05:20:12AM +0300, Avi Kivity wrote: >> >> Why not? To be clear, I'm talking about an io_submit() with >> multiple IO_CMD_FSYNC requests, with a kernel implementation that is >> able to batch these requests. > > IO_CMD_FSYNC doesn't exist right now, but sure, it means we don't have Well, there's IOCB_CMD_FSYNC. But still, this isn't the same thing as what's requested. If I understand correctly, what is requested is a mechanism to flush out all data for multiple file descriptors and follow that with a single barrier/flush (and yes, Ted did give a summary of the commands that would be required to accomplish that). There still remains the question of why this should be tied to the AIO submission interface. Cheers, Jeff