Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262177AbVAEBXK (ORCPT ); Tue, 4 Jan 2005 20:23:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262230AbVAEBWp (ORCPT ); Tue, 4 Jan 2005 20:22:45 -0500 Received: from mail13.syd.optusnet.com.au ([211.29.132.194]:51594 "EHLO mail13.syd.optusnet.com.au") by vger.kernel.org with ESMTP id S262212AbVAEBVa (ORCPT ); Tue, 4 Jan 2005 20:21:30 -0500 Message-ID: <41DB4131.2020400@kolivas.org> Date: Wed, 05 Jan 2005 12:21:53 +1100 From: Con Kolivas User-Agent: Mozilla Thunderbird 1.0 (X11/20041206) X-Accept-Language: en-us, en MIME-Version: 1.0 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 References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 934 Lines: 26 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). > > > Indeed. AIX (sorry) 5.3 on POWER5 explicitly disables SMT (IBM > hyperthreading) if the load doesn't warrant it. > > (Now how about that for Linux?) :) Didn't he say that it degrades performance under load? You're asking to disable it under low load. The 2.6 scheduler is already supposed to try and move tasks to full cores if they're empty instead of smt siblings. Con - 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/