From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261670AbUB0DG7 (ORCPT ); Thu, 26 Feb 2004 22:06:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261678AbUB0DG7 (ORCPT ); Thu, 26 Feb 2004 22:06:59 -0500 Received: from fw.osdl.org ([65.172.181.6]:29327 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S261670AbUB0DGw (ORCPT ); Thu, 26 Feb 2004 22:06:52 -0500 Date: Thu, 26 Feb 2004 19:02:59 -0800 From: "Randy.Dunlap" To: "Grover, Andrew" Cc: mgross@linux.co.intel.com, arjanv@redhat.com, tim.bird@am.sony.com, root@chaos.analogic.com, linux-kernel@vger.kernel.org Subject: Re: Why no interrupt priorities? Message-Id: <20040226190259.7965cc76.rddunlap@osdl.org> In-Reply-To: References: Organization: OSDL X-Mailer: Sylpheed version 0.9.8a (GTK+ 1.2.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 26 Feb 2004 17:36:34 -0800 "Grover, Andrew" wrote: | > On Thursday 26 February 2004 13:30, Arjan van de Ven wrote: | > > hardware IRQ priorities are useless for the linux model. In | > linux, the | > > hardirq runs *very* briefly and then lets the softirq context do the | > > longer taking work. hardware irq priorities then don't matter really | > > because the hardirq's are hardly ever interrupted really, | > and when they | > > are they cause a performance *loss* due to cache trashing. | > The latency | > > added by waiting briefly is going to be really really short | > for any sane | > > hardware. | | Is the assumption that hardirq handlers are superfast also the reason | why Linux calls all handlers on a shared interrupt, even if the first | handler reports it was for its device? Somehow I don't think that's the reasoning. Is there a safe method to determine that there are no other pending interrupts on one shared interrupt? i.e., that other devices don't also have interrupts pending? -- ~Randy