Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750808AbWHGRr4 (ORCPT ); Mon, 7 Aug 2006 13:47:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750809AbWHGRr4 (ORCPT ); Mon, 7 Aug 2006 13:47:56 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:63904 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S1750808AbWHGRr4 (ORCPT ); Mon, 7 Aug 2006 13:47:56 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: "H. Peter Anvin" Cc: "Randy.Dunlap" , Andrew Morton , Andi Kleen , "Protasevich, Natalie" , linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86_64: Make NR_IRQS configurable in Kconfig References: <20060807085924.72f832af.rdunlap@xenotime.net> <44D771A7.7040605@zytor.com> Date: Mon, 07 Aug 2006 11:46:25 -0600 In-Reply-To: <44D771A7.7040605@zytor.com> (H. Peter Anvin's message of "Mon, 07 Aug 2006 10:00:23 -0700") Message-ID: User-Agent: Gnus/5.110004 (No Gnus v0.4) Emacs/21.4 (gnu/linux) 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: 1317 Lines: 31 "H. Peter Anvin" writes: > Eric W. Biederman wrote: >> a) Because I would like to flush out bugs. >> b) Because I want a default that works for everyone. >> c) Because with MSI we have a potential for large irq counts on most systems. >> d) Because anyone who disagrees with me can send a patch and fix >> the default. >> e) Because with the default number of cpus we can very close to needing >> this many irqs in the worst case. >> f) This is much better than previous to my patch and setting NR_CPUS=255 >> and getting 8K IRQS. >> g) Because I probably should have been more inventive than copying the >> NR_IRQS text, but when I did the wording sounded ok to me. >> > > Why not simply reserve 224*NR_CPUS IRQs? If you have 256 CPUs allocating 64K > IRQs should hardly matter :) Well there is this little matter of 224*NR_CPUS*NR_CPUS counters at that point that I think would be prohibitive for most sane people. Taking 224K of per cpu memory in 256 different per cpu areas. Still what is 56MB when you have a terrabyte of RAM. :) Eric - 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/