From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754819AbYHCGyi (ORCPT ); Sun, 3 Aug 2008 02:54:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751470AbYHCGy3 (ORCPT ); Sun, 3 Aug 2008 02:54:29 -0400 Received: from gw.goop.org ([64.81.55.164]:37307 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751241AbYHCGy2 (ORCPT ); Sun, 3 Aug 2008 02:54:28 -0400 Message-ID: <4895561C.2030004@goop.org> Date: Sat, 02 Aug 2008 23:54:20 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: "Eric W. Biederman" CC: Yinghai Lu , "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner , Dhaval Giani , Mike Travis , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86_64: Restore the proper NR_IRQS define so larger systems work. References: <1217642575-22727-1-git-send-email-yhlu.kernel@gmail.com> <86802c440808022258x1198093x7d21274b82e75f4b@mail.gmail.com> In-Reply-To: X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Eric W. Biederman wrote: > Xen pv 64 will work at least as well with a larger definition for > NR_IRQS as it will work with a smaller definition, and since > NR_VECTORS is 256 we always have more irqs with the 32bit definition > we were mistakenly using. > > Xen has 1024 event channels so I expect 1024 would the nice number to > provide there. > Yes, but really its overkill. It needs about 6 interrupts/cpu for normal system overhead (timer, IPI, things like that), and then some amount for virtual devices. dom0 - the control domain - will need some number of events per other guest domain, so it can start feeling the pressure depending on how many domains and devices there are. J