From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750846AbWDDUZV (ORCPT ); Tue, 4 Apr 2006 16:25:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750840AbWDDUZV (ORCPT ); Tue, 4 Apr 2006 16:25:21 -0400 Received: from prgy-npn2.prodigy.com ([207.115.54.38]:8607 "EHLO oddball.prodigy.com") by vger.kernel.org with ESMTP id S1750837AbWDDUZU (ORCPT ); Tue, 4 Apr 2006 16:25:20 -0400 Message-ID: <4432D6D4.2020102@tmr.com> Date: Tue, 04 Apr 2006 16:28:04 -0400 From: Bill Davidsen User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9a1) Gecko/20060330 SeaMonkey/1.5a MIME-Version: 1.0 To: Vishal Patil CC: Linux Kernel Mailing List Subject: Re: CSCAN I/O scheduler for 2.6.10 kernel References: <4745278c0603301955w26fea42eid6bcab91c573eaa3@mail.gmail.com> <4745278c0603301958o4c2ed282x3513fdb459d8ec7c@mail.gmail.com> In-Reply-To: <4745278c0603301958o4c2ed282x3513fdb459d8ec7c@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Vishal Patil wrote: > Maintain two queues which will be sorted in ascending order using Red > Black Trees. When a disk request arrives and if the block number it > refers to is greater than the block number of the current request > being served add (merge) it to the first sorted queue or else add > (merge) it to the second sorted queue. Keep on servicing the requests > from the first request queue until it is empty after which switch over > to the second queue and now reverse the roles of the two queues. > Simple and Sweet. Many thanks for the awesome block I/O layer in the > 2.6 kernel. > Why both queues sorting in ascending order? I would think that one should be in descending order, which would reduce the seek distance between the last i/o on one queue and the first on the next. -- -bill davidsen (davidsen@tmr.com) "The secret to procrastination is to put things off until the last possible moment - but no longer" -me