Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 6 Feb 2001 12:37:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 6 Feb 2001 12:37:25 -0500 Received: from zeus.kernel.org ([209.10.41.242]:52174 "EHLO zeus.kernel.org") by vger.kernel.org with ESMTP id ; Tue, 6 Feb 2001 12:37:06 -0500 Date: Tue, 6 Feb 2001 17:34:37 +0000 From: "Stephen C. Tweedie" To: Alan Cox Cc: Anders Eriksson , linux-kernel@vger.kernel.org, Stephen Tweedie Subject: Re: sync & asyck i/o Message-ID: <20010206173437.A19836@redhat.com> In-Reply-To: <200102061424.PAA32284@hell.wii.ericsson.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from alan@lxorguk.ukuu.org.uk on Tue, Feb 06, 2001 at 02:52:40PM +0000 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Tue, Feb 06, 2001 at 02:52:40PM +0000, Alan Cox wrote: > > According to the man page for fsync it copies in-core data to disk > > prior to its return. Does that take async i/o to the media in account? > > I.e. does it wait for completion of the async i/o to the disk? > > Undefined. > In practice some IDE disks do write merging and small amounts of write > caching in the drive firmware so you cannot trust it 100%. It's worth noting that it *is* defined unambiguously in the standards: fsync waits until all the data is hard on disk. Linux will obey that if it possibly can: only in cases where the hardware is actively lying about when the data has hit disk will the guarantee break down. --Stephen - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/