Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 15 Mar 2002 03:59:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 15 Mar 2002 03:59:42 -0500 Received: from mx2.elte.hu ([157.181.151.9]:16571 "HELO mx2.elte.hu") by vger.kernel.org with SMTP id ; Fri, 15 Mar 2002 03:59:26 -0500 Date: Fri, 15 Mar 2002 08:55:19 +0100 (CET) From: Ingo Molnar Reply-To: mingo@elte.hu To: Bill Davidsen Cc: Linux Kernel mailing list Subject: Re: Severe IRQ problems on Foster (P4 Xeon) system 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 On Wed, 13 Mar 2002, Bill Davidsen wrote: > > i've written a patch for this, it's enclosed in this email. It implements > > a brownean motion of IRQs, based on load patterns. The concept works > > really well on Foster CPUs - eg. it will redirect IRQs to idle CPUs - but > > if all CPUs are idle then the IRQs are randomly and evenly distributed > > between CPUs. > > If several processors are idle, say CPU0 busy and CPU[123] idle, does it > preferentially use a "CPU" on another chip? And does that make any > difference? It's not clear to me if the HT CPUs share cache or not, they > obviously share bandwidth from L2 to RAM. it has no HT affinity knowledge yet, but adding it should be straightforward. The IRQ 'move' function is in the slow path and can be made HT-aware without any performance-worries. Ingo - 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/