From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladislav Bolkhovitin Subject: Re: [sqlite] light weight write barriers Date: Mon, 12 Nov 2012 22:37:39 -0500 Message-ID: <50A1C083.6080904@vlnb.net> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: General Discussion of SQLite Database , Alan Cox , Vladislav Bolkhovitin , Theodore Ts'o , drh@hwaci.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org To: Howard Chu Return-path: Received: from moutng.kundenserver.de ([212.227.126.171]:65180 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751897Ab2KMDht (ORCPT ); Mon, 12 Nov 2012 22:37:49 -0500 In-Reply-To: <50931601.4060102@symas.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Howard Chu, on 11/01/2012 08:38 PM wrote: > Alan Cox wrote: >>> How about that recently preliminary infrastructure to send ORDERED commands >>> instead of queue draining was deleted from the kernel, because "there's no >>> difference where to drain the queue, on the kernel or the storage side"? >> >> Send patches. > > 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 > c) cheap drives won't support barriers This is why it is so important for performance to use all storage capabilities. Particularly, ORDERED commands instead of trying to pretend be smarter, than the storage, doing queue draining. Vlad