From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267191AbUHDBvW (ORCPT ); Tue, 3 Aug 2004 21:51:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267193AbUHDBvW (ORCPT ); Tue, 3 Aug 2004 21:51:22 -0400 Received: from holomorphy.com ([207.189.100.168]:35768 "EHLO holomorphy.com") by vger.kernel.org with ESMTP id S267191AbUHDBvU (ORCPT ); Tue, 3 Aug 2004 21:51:20 -0400 Date: Tue, 3 Aug 2004 18:51:15 -0700 From: William Lee Irwin III To: Peter Williams Cc: Linux Kernel Mailing List , Michal Kaczmarski , Shane Shrybman Subject: Re: [PATCH] V-3.0 Single Priority Array O(1) CPU Scheduler Evaluation Message-ID: <20040804015115.GF2334@holomorphy.com> Mail-Followup-To: William Lee Irwin III , Peter Williams , Linux Kernel Mailing List , Michal Kaczmarski , Shane Shrybman References: <410DDFD2.5090400@bigpond.net.au> <20040802134257.GE2334@holomorphy.com> <410EDD60.8040406@bigpond.net.au> <20040803020345.GU2334@holomorphy.com> <410F08D6.5050200@bigpond.net.au> <20040803104912.GW2334@holomorphy.com> <41102FE5.9010507@bigpond.net.au> <20040804005034.GE2334@holomorphy.com> <41103DBB.6090100@bigpond.net.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <41103DBB.6090100@bigpond.net.au> User-Agent: Mutt/1.5.6+20040523i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org William Lee Irwin III wrote: >> Aperiodic rotations defer movement until MAX_RT_PRIO's slot is evacuated. On Wed, Aug 04, 2004 at 11:36:59AM +1000, Peter Williams wrote: > Unfortunately, to ensure no starvation, promotion has to continue even > when there are tasks in MAX_RT_PRIO's slot. One may either demote to evict MAX_RT_PRIO immediately prior to rotation or rely on timeslice expiry to evict MAX_RT_PRIO. Forcibly evicting MAX_RT_PRIO undesirably accumulates tasks at the fencepost. William Lee Irwin III wrote: >> The primary concern was that ticklessness etc. may require it to occur >> during context switches. On Wed, Aug 04, 2004 at 11:36:59AM +1000, Peter Williams wrote: > On a tickless system, I'd consider using a timer to control when > do_promotions() gets called. I imagine something similar will be > necessary to manage time slices? This is an alternative to scheduler accounting in context switches. Periodicity often loses power conservation benefits. -- wli