From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751215AbWDXVUz (ORCPT ); Mon, 24 Apr 2006 17:20:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751262AbWDXVUz (ORCPT ); Mon, 24 Apr 2006 17:20:55 -0400 Received: from mx1.redhat.com ([66.187.233.31]:5270 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1751215AbWDXVUy (ORCPT ); Mon, 24 Apr 2006 17:20:54 -0400 Date: Mon, 24 Apr 2006 17:20:38 -0400 From: Alan Cox To: Linus Torvalds Cc: Arjan van de Ven , Alan Cox , Stephen Hemminger , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: better leve triggered IRQ management needed Message-ID: <20060424212038.GC4942@devserv.devel.redhat.com> References: <20060424114105.113eecac@localhost.localdomain> <1145908402.3116.63.camel@laptopd505.fenrus.org> <20060424201646.GA23517@devserv.devel.redhat.com> <1145911417.3116.69.camel@laptopd505.fenrus.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 24, 2006 at 02:07:01PM -0700, Linus Torvalds wrote: > debugging standpoint. So even if it's just that every registered SA_SHIRQ > would get a heartbeat at least once every five seconds (and we'd limit it > to SA_SHIRQ exactly because a driver that doesn't have that set may get > confused if it gets extra interrupts), that might sound totally useless, > but it might actually help somebody who otherwise might just make a pretty > useless "the machine hung" bug-report. Have to watch enable/disable_irq and the other races here. > The fake interrupt could even print out a warning if somebody returns > SA_HANDLED (since normally there _shouldn't_ have been any work to handle > for it), and if that means that for somebody, things go from "the machine > hung" to "the machine got very slow, and printed out 'fake interrupt for > ide0 returned SA_HANDLED!'", that would potentially be a big debug aid. There are high rate IRQ sources that would trigger that erratically due to races but it could be useful in some kind of "linux irqdebug" mode > We've had our ass saved quite a few times now by the irq storm detector > ("irq X: nobody cared" and friends), which has helped debug irqs that > haven't been set up properly, that I'm convinced things like this might > well make a huge deal. Yep Alan -- "... and for $64000 question, could you get yourself vaguely familiar with the notion of on-topic posting?" -- Al Viro