Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262391AbVADW5b (ORCPT ); Tue, 4 Jan 2005 17:57:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261732AbVADWzI (ORCPT ); Tue, 4 Jan 2005 17:55:08 -0500 Received: from mail.dif.dk ([193.138.115.101]:36245 "EHLO mail.dif.dk") by vger.kernel.org with ESMTP id S262397AbVADWyZ (ORCPT ); Tue, 4 Jan 2005 17:54:25 -0500 Date: Wed, 5 Jan 2005 00:05:45 +0100 (CET) From: Jesper Juhl To: Nicholas Berry Cc: grendel@caudium.net, willy@w.ods.org, linux-kernel@vger.kernel.org Subject: Re: Very high load on P4 machines with 2.4.28 In-Reply-To: Message-ID: References: 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: 1093 Lines: 28 On Tue, 4 Jan 2005, Nicholas Berry wrote: > >>> Willy Tarreau 01/04/05 5:05 PM >>> > >> Oh, while I'm at it, are you using hyperthreading, and if so, could > you > >> disable it ? I have seen many cases where it degrades performances > >> significantly (eg: highly loaded user space network applications). > > >Willy > > Indeed. AIX (sorry) 5.3 on POWER5 explicitly disables SMT (IBM > hyperthreading) if the load doesn't warrant it. > Heh, yeah, that's pretty funky. I was initially pretty baffled first time topas on a AIX 5.3 box showed me I had 6 CPU's but quitting it and starting it 2sec later showed me 8 CPU's (box has 4 physical CPUs). That send me hunting through docs. On the surface it seems like a nice feature, but if it makes any real difference or not I've had difficulty in determining. -- Jesper Juhl - 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/