Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752891Ab1BPQM2 (ORCPT ); Wed, 16 Feb 2011 11:12:28 -0500 Received: from smtp02.citrix.com ([66.165.176.63]:26370 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752850Ab1BPQMZ (ORCPT ); Wed, 16 Feb 2011 11:12:25 -0500 X-IronPort-AV: E=Sophos;i="4.60,480,1291611600"; d="scan'208";a="136169527" Subject: Re: Xen and incorporating event channels in to nr_irqs From: Ian Campbell To: Thomas Gleixner CC: xen-devel , linux-kernel , Peter Zijlstra , "Ingo Molnar" In-Reply-To: References: <1297868399.16356.180.camel@zakaz.uk.xensource.com> Content-Type: text/plain; charset="UTF-8" Organization: Citrix Systems, Inc. Date: Wed, 16 Feb 2011 16:12:19 +0000 Message-ID: <1297872739.16356.261.camel@zakaz.uk.xensource.com> MIME-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1449 Lines: 35 On Wed, 2011-02-16 at 15:56 +0000, Thomas Gleixner wrote: > I'm about to remove the nr_irqs NR_IRQS limitation. It's silly when we > deal with sparse irqs. So the idea is to have the initial nr_irqs set > in early boot to have a sensible size for allocating stuff. Later on > we can expand nr_irqs when the need arises. > It's not only Xen which wants to eliminate the limitation. Think about > irq expanders which are detected late in the boot. We have no sensible > way to reserve enough numbers for them at early boot as we dont know > whether that hardware is there or not. > > So my plan for .39 is to ignore the NR_IRQS limitation in the sparse > case and make nr_irqs expandable of course with a sensible upper limit > in the core code itself. It's basically the allocation bitmap which > limits it, but I doubt we'll hit 1 Million irq numbers in the > forseeable future. That sounds ideal, thanks! I was hoping to get rid of the workaround in Xen events.c in the 2.6.39 timeframe too. If you let me know when you have something I can test I'll combine with the Xen side and give it a spin. On a vaguely related note, what is the future of non-sparse IRQs (on x86 and/or generally)? Ian. -- 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/