From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932758Ab2DTPUd (ORCPT ); Fri, 20 Apr 2012 11:20:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:62067 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932512Ab2DTPUc (ORCPT ); Fri, 20 Apr 2012 11:20:32 -0400 From: Jeff Moyer To: Dave Kleikamp Cc: "Maxim V. Patlasov" , "linux-fsdevel\@vger.kernel.org" , "linux-kernel\@vger.kernel.org" , Zach Brown Subject: Re: [RFC PATCH v2 15/21] loop: use aio to perform io on the underlying file References: <1333122228-13633-1-git-send-email-dave.kleikamp@oracle.com> <1333122228-13633-16-git-send-email-dave.kleikamp@oracle.com> <4F917751.9040600@parallels.com> <4F917C2F.4020805@oracle.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: Fri, 20 Apr 2012 11:20:25 -0400 In-Reply-To: <4F917C2F.4020805@oracle.com> (Dave Kleikamp's message of "Fri, 20 Apr 2012 10:09:35 -0500") 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 Dave Kleikamp writes: > On 04/20/2012 09:48 AM, Maxim V. Patlasov wrote: >> On 03/30/2012 07:43 PM, Dave Kleikamp wrote: >>> From: Zach Brown >>> >>> This uses the new kernel aio interface to process loopback IO by >>> submitting concurrent direct aio. Previously loop's IO was serialized >>> by synchronous processing in a thread. >>> >> >> The patch ignores REQ_FLUSH bit of bi_rw. Is it simply overlook? > > Good question. Since the loop device is sending only direct IO requests, > it shouldn't be necessary to explicitly flush page cache, but REQ_FLUSH REQ_FLUSH isn't about the page cache, it's about flushing the volatile disk write cache. You need to handle that. Cheers, Jeff