From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262033AbTL3Alv (ORCPT ); Mon, 29 Dec 2003 19:41:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262092AbTL3Alv (ORCPT ); Mon, 29 Dec 2003 19:41:51 -0500 Received: from tmr-02.dsl.thebiz.net ([216.238.38.204]:46855 "EHLO gatekeeper.tmr.com") by vger.kernel.org with ESMTP id S262033AbTL3Alt (ORCPT ); Mon, 29 Dec 2003 19:41:49 -0500 To: linux-kernel@vger.kernel.org Path: gatekeeper.tmr.com!davidsen From: davidsen@tmr.com (bill davidsen) Newsgroups: mail.linux-kernel Subject: Re: [PATCH] 2.6.0 batch scheduling, HT aware Date: 30 Dec 2003 00:29:58 GMT Organization: TMR Associates, Schenectady NY Message-ID: References: <200312231138.21734.kernel@kolivas.org> <200312271042.55989.kernel@kolivas.org> <20031227110903.GA1413@elf.ucw.cz> <200312272215.01563.kernel@kolivas.org> X-Trace: gatekeeper.tmr.com 1072744198 16001 192.168.12.62 (30 Dec 2003 00:29:58 GMT) X-Complaints-To: abuse@tmr.com Originator: davidsen@gatekeeper.tmr.com Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In article <200312272215.01563.kernel@kolivas.org>, Con Kolivas wrote: | On Sat, 27 Dec 2003 22:09, Pavel Machek wrote: | > So... even on normal SMP, | > "task-on-other-cpu-slows-down-task-on-this-cpu" effect exists. Okay, | > it is not as visible as on HT machine (50% slowdown), but its | > definitely there. | | Sure but I think we're getting pedantic here. The problem is really simple - a | uniprocessor HT desktop booted in SMP mode feels half the speed while running | setiathome (or video encoding or whatever cpu bound task) compared to booting | it in UP mode. So, ironically, enabling the HT makes the machine feel slower | when running multiple tasks. And there will be a heck of a lot of these in | the future. Let me put forth a thought, without a solution. In the case you describe, what is needed, and not provided in hardware, is a way to do priority within the CPU, so in the case of a contested resource there is a way to ensure the process we wish wins. Since that seems unavailable in Intel, do other CPUs do better (or different)? -- bill davidsen CTO, TMR Associates, Inc Doing interesting things with little computers since 1979.