From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755706AbXHNIBZ (ORCPT ); Tue, 14 Aug 2007 04:01:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751265AbXHNIBJ (ORCPT ); Tue, 14 Aug 2007 04:01:09 -0400 Received: from mx10.go2.pl ([193.17.41.74]:33135 "EHLO poczta.o2.pl" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752098AbXHNIBH (ORCPT ); Tue, 14 Aug 2007 04:01:07 -0400 Date: Tue, 14 Aug 2007 10:01:52 +0200 From: Jarek Poplawski To: Benjamin Herrenschmidt Cc: Thomas Gleixner , Andrew Morton , Linus Torvalds , LKML , Ingo Molnar , Stable Team , Jean-Baptiste Vignaud , "marcin\.slusarz" Subject: Re: [patch 3/3] genirq: mark io_apic level interrupts to avoid resend Message-ID: <20070814080152.GB1702@ff.dom.local> References: <20070812152213.551812576@inhelltoy.tec.linutronix.de> <20070812152303.177006193@inhelltoy.tec.linutronix.de> <20070813112821.GA2863@ff.dom.local> <1187006835.12828.112.camel@chaos> <20070813135311.GB4026@ff.dom.local> <1187032057.5330.17.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1187032057.5330.17.camel@localhost.localdomain> User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 13, 2007 at 02:07:37PM -0500, Benjamin Herrenschmidt wrote: > On Mon, 2007-08-13 at 15:53 +0200, Jarek Poplawski wrote: > > > > I've thought e.g. about "fasteoi" for this "Virtual Wire" timer for > > i386: I hope it's OK, but since is it any problem to add some comment > > here, why it's OK with resending here (with POWERPC it's easier to > > think it's something special, but here we have to similar things in > > the same file)? Sorry! Of course, there is something about edge in a lapic_chip declaration, so this (plus some knowledge of the subject) should be enough, but I was a little surprised that x86_64 uses handle_edge_irq for probably(?) the same thing. > > To be totally fair, there shouldn't be a problem with spurrious > re-sends, I'm not sure what problems some chipsets are having there, > though it may be related to the method used for re-sending. On ppc, we > use the soft method I think everywhere anyway. IMHO, this method is very doubtful if the whole system isn't adapted for this: e.g. in networking code softirqs are blocked very often, so such resended irq could be really late. > > I use re-sending on cell with fasteoi for the on-die top-level PIC > because while it does have a HW priority handling, it also doesn't have > a HW mask. Thus I just "drop" IRQs that are masked and resend (it's edge > messages). So, if I got this right, it looks a bit easier, since you can resend with the same type as not masked ones (fasteoi-edge?!), I guess. Regards, Jarek P.