From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932167Ab0ICVsR (ORCPT ); Fri, 3 Sep 2010 17:48:17 -0400 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:53656 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932118Ab0ICVsQ (ORCPT ); Fri, 3 Sep 2010 17:48:16 -0400 Date: Fri, 03 Sep 2010 14:48:33 -0700 (PDT) Message-Id: <20100903.144833.108785087.davem@davemloft.net> To: akepner@sgi.com Cc: linux-kernel@vger.kernel.org Subject: Re: [RFC/PATCH] notify user-level IRQ balancer when kernel assigns IRQ affinity From: David Miller In-Reply-To: <20100903210554.GO2464@sgi.com> References: <20100903210554.GO2464@sgi.com> X-Mailer: Mew version 6.3 on Emacs 23.1 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Arthur Kepner Date: Fri, 3 Sep 2010 14:05:54 -0700 > > We've run into situations where a CPU runs out of interrupt > vectors, because all the interrupts are getting the default > affinity (and the interrupt balancer hasn't yet run). > > The following emits a netlink message whenever an interrupt > is given a default CPU affinity. A user-level IRQ balancer > can use those messages to decide if, and how to reassign > affinities. This should allow us to avoid running out of > vectors on any particular CPU (or at least make it far less > likely). > > I know this needs work, but would like to get comments on > the idea before doing more coding and testing. > > Signed-off-by: Arthur Kepner As I replied to you on netdev, this can't possibly work. Interrupt allocation needs to work properly before userspace even starts up. So the allocation management must be inside of the kernel entirely.