Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753420AbZCBMZ6 (ORCPT ); Mon, 2 Mar 2009 07:25:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751809AbZCBMZu (ORCPT ); Mon, 2 Mar 2009 07:25:50 -0500 Received: from brick.kernel.dk ([93.163.65.50]:59559 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751747AbZCBMZu (ORCPT ); Mon, 2 Mar 2009 07:25:50 -0500 Date: Mon, 2 Mar 2009 13:25:48 +0100 From: Jens Axboe To: ???? Cc: linux-kernel@vger.kernel.org Subject: Re: The difference of request dir between AS and Deadline I/O scheduler? Message-ID: <20090302122547.GT11787@kernel.dk> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 870 Lines: 27 On Mon, Mar 02 2009, ???? wrote: > Hi, > > I'm little confused about the defination of request dir in AS and > Deadline I/O scheduler. > In AS, the request dir is defined by wheher it's sync: > > data_dir = rq_is_sync(rq); > > But in Deadline, the requests are grouped by read and write. > > Why is there the difference since AS is an extension of Deadline? > what's the consideration? Because AS uses the sync vs async distinction to decide whether to anticipate a new request from that process. 'sync' is then reads or sync writes, whereas deadline does not distinguish between sync and async writes. -- Jens Axboe -- 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/