Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S271107AbTG1VqH (ORCPT ); Mon, 28 Jul 2003 17:46:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S271117AbTG1VqH (ORCPT ); Mon, 28 Jul 2003 17:46:07 -0400 Received: from tmr-02.dsl.thebiz.net ([216.238.38.204]:12806 "EHLO gatekeeper.tmr.com") by vger.kernel.org with ESMTP id S271107AbTG1VqE (ORCPT ); Mon, 28 Jul 2003 17:46:04 -0400 Date: Mon, 28 Jul 2003 17:38:16 -0400 (EDT) From: Bill Davidsen To: Ingo Molnar cc: Con Kolivas , linux-kernel@vger.kernel.org Subject: Re: [patch] sched-2.6.0-test1-G6, interactivity changes In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1696 Lines: 38 On Mon, 28 Jul 2003, Ingo Molnar wrote: > > On Mon, 28 Jul 2003, Con Kolivas wrote: > > > On Sun, 27 Jul 2003 23:40, Ingo Molnar wrote: > > > - further increase timeslice granularity > > > > For a while now I've been running a 1000Hz 2.4 O(1) kernel tree that > > uses timeslice granularity set to MIN_TIMESLICE which has stark > > smoothness improvements in X. I've avoided promoting this idea because > > of the theoretical drop in throughput this might cause. I've not been > > able to see any detriment in my basic testing of this small granularity, > > so I was curious to see what you throught was a reasonable lower limit? > > it's a hard question. The 25 msecs in -G6 is probably too low. It would seem to me that the lower limit for a given CPU is a function of CPU speed and cache size. One reason for longer slices is to preserve the cache, but the real time to get good use from the cache is not a constant, and you just can't pick any one number which won't be too short on a slow cpu or unproductively long on a fast CPU. Hyperthreading shrinks the effective cache size as well, but certainly not by 2:1 or anything nice. Perhaps this should be a tunable set by a bit of hardware discovery at boot and diddled at your own risk. Sure one factor in why people can't agree on HZ and all to get best results. -- bill davidsen CTO, TMR Associates, Inc Doing interesting things with little computers since 1979. - 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/