Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752559AbZK2P3K (ORCPT ); Sun, 29 Nov 2009 10:29:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751233AbZK2P3K (ORCPT ); Sun, 29 Nov 2009 10:29:10 -0500 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:43261 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750958AbZK2P3J (ORCPT ); Sun, 29 Nov 2009 10:29:09 -0500 Date: Sun, 29 Nov 2009 15:27:57 +0000 From: Russell King - ARM Linux To: Jamie Lokier Cc: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , David Brownell , Eric Miao , Peter Zijlstra , John Stultz , Rusty Russell , LKML , Ingo Molnar , Thomas Gleixner , Nicolas Pitre , Andrew Morton , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] warn about shared irqs requesting IRQF_DISABLED registered with setup_irq Message-ID: <20091129152757.GF11445@n2100.arm.linux.org.uk> References: <20091127195857.GB28193@n2100.arm.linux.org.uk> <1259356206-14843-1-git-send-email-u.kleine-koenig@pengutronix.de> <20091128200344.GA1272@pengutronix.de> <20091129023118.GA21529@shareable.org> <20091129102635.GA22653@pengutronix.de> <20091129151840.GA30813@shareable.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091129151840.GA30813@shareable.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 914 Lines: 19 On Sun, Nov 29, 2009 at 03:18:40PM +0000, Jamie Lokier wrote: > Or we could do away with this silliness and just switch everything to > threaded interrupts with RT-priorities ;-) ... thereby needlessly increasing the latency of all interrupt handling and probably breaking some devices. Some devices (eg, SMC91x, serial ports, PIO audio - AACI, MMCI) are _extremely_ sensitive to interrupt latency due to lack of FIFO depth. MMCI already sees overruns on ARM platforms if you try and clock the cards at anything over about 500kHz. Adding any more latency means reducing the maximum clock rate there, and therefore crippling throughput even more than it is already. -- 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/