Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756624AbYLEMS3 (ORCPT ); Fri, 5 Dec 2008 07:18:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751870AbYLEMSU (ORCPT ); Fri, 5 Dec 2008 07:18:20 -0500 Received: from one.firstfloor.org ([213.235.205.2]:48801 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751667AbYLEMSU (ORCPT ); Fri, 5 Dec 2008 07:18:20 -0500 Date: Fri, 5 Dec 2008 13:29:30 +0100 From: Andi Kleen To: Alan Cox Cc: Andi Kleen , Mikulas Patocka , linux-kernel@vger.kernel.org, xfs@oss.sgi.com, Alasdair G Kergon , Andi Kleen , Milan Broz Subject: Re: Device loses barrier support (was: Fixed patch for simple barriers.) Message-ID: <20081205122930.GB6703@one.firstfloor.org> References: <20081204145810.GR6703@one.firstfloor.org> <20081204174838.GS6703@one.firstfloor.org> <20081204221551.GV6703@one.firstfloor.org> <20081205004849.GX6703@one.firstfloor.org> <20081205013739.GZ6703@one.firstfloor.org> <20081205115225.13c277ee@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20081205115225.13c277ee@lxorguk.ukuu.org.uk> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 891 Lines: 22 > Not when the fundamental design of the code is broken and trashes > performance. Sorry but that's just not correct. There's nothing in late failing barriers that "trashes performance". The file system writers have to be careful to handle it, but at least the current ones all do. And also if someone writes a hypothetical fully asynchronously driven barrier based IO transaction system it would be still possible to handle the late failing barrier without too many complications. Also late failing barriers is pretty much the only sane way to implement barriers in software remapping schemes like DM and MD. -Andi -- ak@linux.intel.com -- 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/