From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261976AbUCaOIo (ORCPT ); Wed, 31 Mar 2004 09:08:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261980AbUCaOIo (ORCPT ); Wed, 31 Mar 2004 09:08:44 -0500 Received: from mx1.redhat.com ([66.187.233.31]:17896 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S261976AbUCaOIl (ORCPT ); Wed, 31 Mar 2004 09:08:41 -0500 Subject: Re: [PATCH] barrier patch set From: "Stephen C. Tweedie" To: Jeff Garzik Cc: Chris Mason , Bartlomiej Zolnierkiewicz , Jens Axboe , Linux Kernel , Stephen Tweedie In-Reply-To: <4069F2FC.90003@pobox.com> References: <20040319153554.GC2933@suse.de> <200403201723.11906.bzolnier@elka.pw.edu.pl> <1079800362.11062.280.camel@watt.suse.com> <200403201805.26211.bzolnier@elka.pw.edu.pl> <1080662685.1978.25.camel@sisko.scot.redhat.com> <1080674384.3548.36.camel@watt.suse.com> <1080683417.1978.53.camel@sisko.scot.redhat.com> <4069F2FC.90003@pobox.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit Organization: Message-Id: <1080742105.1991.40.camel@sisko.scot.redhat.com> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.2 (1.2.2-5) Date: 31 Mar 2004 15:08:25 +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Tue, 2004-03-30 at 23:21, Jeff Garzik wrote: > For IDE, O_DIRECT and O_SYNC can use special "FUA" commands, which don't > return until the data is on the platter. fsync() is still really nasty, because that can require that we wait on IO that was submitted by the VM before we knew that there was a synchronous IO wait coming. SCSI also has an FUA bit that can make a difference if you've got writeback caching enabled. (And FUA on read can bypass drive writethrough caches, too, for media verification.) --Stephen