From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262694AbTLHU4h (ORCPT ); Mon, 8 Dec 2003 15:56:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262714AbTLHU4h (ORCPT ); Mon, 8 Dec 2003 15:56:37 -0500 Received: from pix-525-pool.redhat.com ([66.187.233.200]:21255 "EHLO devserv.devel.redhat.com") by vger.kernel.org with ESMTP id S262694AbTLHU4d (ORCPT ); Mon, 8 Dec 2003 15:56:33 -0500 Date: Mon, 8 Dec 2003 15:55:56 -0500 (EST) From: Ingo Molnar X-X-Sender: mingo@devserv.devel.redhat.com To: Zwane Mwaikambo cc: Nick Piggin , Anton Blanchard , Linus Torvalds , Andrew Morton , Rusty Russell , linux-kernel Subject: Re: [PATCH][RFC] make cpu_sibling_map a cpumask_t In-Reply-To: Message-ID: References: <3FD3FD52.7020001@cyberone.com.au> 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 On Mon, 8 Dec 2003, Zwane Mwaikambo wrote: > > P.S. > > I have an alternative to Ingo's HT scheduler which basically does > > the same thing. It is showing a 20% elapsed time improvement with a > > make -j3 on a 2xP4 Xeon (4 logical CPUs). > > -j3 is an odd number, what does -j4, -j8, -j16 look like? let me guess: -j3 is the one that gives the highest performance boost on a 2-way/4-logical P4 box? for the SMT/HT scheduler to give any benefits there has to be idle time - so that SMT decisions actually make a difference. the higher -j values are only useful to make sure that SMT scheduling does not introduce regressions - performance should be the same as the pure SMP/NUMA scheduler's performance. Ingo