Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760852Ab2KBM3G (ORCPT ); Fri, 2 Nov 2012 08:29:06 -0400 Received: from lxorguk.ukuu.org.uk ([81.2.110.251]:36046 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759315Ab2KBM3E (ORCPT ); Fri, 2 Nov 2012 08:29:04 -0400 Date: Fri, 2 Nov 2012 12:33:59 +0000 From: Alan Cox To: Howard Chu Cc: General Discussion of SQLite Database , Vladislav Bolkhovitin , "Theodore Ts'o" , drh@hwaci.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [sqlite] light weight write barriers Message-ID: <20121102123359.2479a7dc@pyramind.ukuu.org.uk> In-Reply-To: <50931601.4060102@symas.com> References: <5086F5A7.9090406@vlnb.net> <20121025051445.GA9860@thunk.org> <508B3EED.2080003@vlnb.net> <20121027044456.GA2764@thunk.org> <5090532D.4050902@vlnb.net> <20121031095404.0ac18a4b@pyramind.ukuu.org.uk> <5092D90F.7020105@vlnb.net> <20121101212418.140e3a82@pyramind.ukuu.org.uk> <50931601.4060102@symas.com> X-Mailer: Claws Mail 3.8.1 (GTK+ 2.24.8; x86_64-redhat-linux-gnu) Face: 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 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1028 Lines: 24 > Isn't any type of kernel-side ordering an exercise in futility, since > a) the kernel has no knowledge of the disk's actual geometry > b) most drives will internally re-order requests anyway They will but only as permitted by the commands queued, so you have some control depending upon the interface capabilities. > c) cheap drives won't support barriers Barriers are pretty much universal as you need them for power off ! > Even assuming the drives honored all your requests without lying, how would > you really want this behavior exposed? From the userland perspective, there > are very few apps that care. Probably only transactional databases, really. And file systems internally sometimes. A file system is after all a transactional database of sorts. Alan -- 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/