Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262494AbTE0Cb1 (ORCPT ); Mon, 26 May 2003 22:31:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262499AbTE0Cb0 (ORCPT ); Mon, 26 May 2003 22:31:26 -0400 Received: from holomorphy.com ([66.224.33.161]:13257 "EHLO holomorphy") by vger.kernel.org with ESMTP id S262494AbTE0CbX (ORCPT ); Mon, 26 May 2003 22:31:23 -0400 Date: Mon, 26 May 2003 19:44:19 -0700 From: William Lee Irwin III To: Zwane Mwaikambo Cc: Andrew Morton , davem@redhat.com, andrea@suse.de, davidsen@tmr.com, haveblue@us.ibm.com, habanero@us.ibm.com, mbligh@aracnet.com, linux-kernel@vger.kernel.org Subject: Re: userspace irq balancer Message-ID: <20030527024419.GF8978@holomorphy.com> Mail-Followup-To: William Lee Irwin III , Zwane Mwaikambo , Andrew Morton , davem@redhat.com, andrea@suse.de, davidsen@tmr.com, haveblue@us.ibm.com, habanero@us.ibm.com, mbligh@aracnet.com, linux-kernel@vger.kernel.org References: <20030527000639.GA3767@dualathlon.random> <20030526.171527.35691510.davem@redhat.com> <20030527004115.GD3767@dualathlon.random> <20030526.174841.116378513.davem@redhat.com> <20030527015307.GC8978@holomorphy.com> <20030526185920.64e9751f.akpm@digeo.com> <20030527021002.GD8978@holomorphy.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: The Domain of Holomorphy User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1119 Lines: 23 On Mon, 26 May 2003, William Lee Irwin III wrote: >> The number of interrupt sources on a system ends up scaling this up to >> numerous IO-APIC RTE reprograms and ioapic_lock acquisitions per-second >> (granted, with a 5s timeout between reprogramming storms) where it >> competes against IO-APIC interrupt acknowledgements. >> Making the lock per- IO-APIC would at least put a bound on the number >> of competitors mutually interfering with each other, but a tighter >> bound on the amount of work than NR_IRQS would be more useful than that. On Mon, May 26, 2003 at 10:15:23PM -0400, Zwane Mwaikambo wrote: > Ok there are 16 IOAPICs on an 8quad, but really if we start banging on > that lock someone is doing way too much hardware access... It's done to acknowledge every interrupt. Also, there is additional cost associated with bouncing the lock's cacheline. -- wli - 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/