From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 21 Nov 2002 20:04:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 21 Nov 2002 20:04:41 -0500 Received: from holomorphy.com ([66.224.33.161]:52355 "EHLO holomorphy") by vger.kernel.org with ESMTP id ; Thu, 21 Nov 2002 20:04:40 -0500 Date: Thu, 21 Nov 2002 17:08:53 -0800 From: William Lee Irwin III To: Bill Davidsen Cc: Hugh Dickins , lkml , linux-mm@kvack.org Subject: Re: 2.5.48-mm1 Message-ID: <20021122010853.GI11776@holomorphy.com> Mail-Followup-To: William Lee Irwin III , Bill Davidsen , Hugh Dickins , lkml , linux-mm@kvack.org References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.3.25i Organization: The Domain of Holomorphy Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 21, 2002 at 04:04:25PM -0500, Bill Davidsen wrote: > This is purely a performance decision. If you want to avoid bad latency on > reads then you have to throttle writes. The loop_thread will make the > system just as slow as a user application writing the same number of > pages. > If you want io scheduling you will deliberately slow writes to let reads > happen in reasonable time. And vice-versa I imagine, although I don't > think I've seen that case. Not entirely so. This is just a scheduling decision that has to discriminate between blocking and nonblocking requests and prevent starvation of the blocking requests. Write throttling is an oversimplification that functions poorly. Bill