From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261987AbVFWDos (ORCPT ); Wed, 22 Jun 2005 23:44:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262021AbVFWDor (ORCPT ); Wed, 22 Jun 2005 23:44:47 -0400 Received: from thunder.netspace.net.au ([203.10.110.71]:31495 "EHLO mail.netspace.net.au") by vger.kernel.org with ESMTP id S261987AbVFWDod (ORCPT ); Wed, 22 Jun 2005 23:44:33 -0400 Message-ID: <42BA300D.9080106@netspace.net.au> Date: Thu, 23 Jun 2005 11:44:13 +0800 From: Andrew Lewis User-Agent: Mozilla Thunderbird 1.0.2 (Windows/20050317) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Russell King Cc: Daniel Walker , "Eugeny S. Mints" , linux-kernel@vger.kernel.org, Ingo Molnar Subject: Re: ARM Linux Suitability for Real-time Application References: <20050622100231.A28181@flint.arm.linux.org.uk> <20050622182250.A13976@flint.arm.linux.org.uk> In-Reply-To: <20050622182250.A13976@flint.arm.linux.org.uk> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Russell King wrote: > On Wed, Jun 22, 2005 at 09:52:40AM -0700, Daniel Walker wrote: > >>On Wed, 22 Jun 2005, Russell King wrote: >> >>>If you're just after some background process to run off interrupts with >>>minimal interrupt latency, the good news is that you don't have to modify >>>the kernel on ARM, and you certainly don't need any RT patches. >>> >>>If you use the FIQ, then your FIQ latency will be the time it takes the >>>CPU to enter your FIQ function. Since the kernel _never_ disables FIQs >>>in any way, FIQs have ultimate priority over everything else in the >>>system. >>> >> >>Aren't FIQ's only on some ARM's ? > > > Yes, but please read the original mail. I think you'll find my reply > is completely relevant to the question being posed, which was based > upon the AT91RM9200 SoC. Thanks for the suggestions. The FIQ solutions sounds like the one to use. I'll probably do a little testing sometime in the next few weeks to determine the maximum loading I can place on the processor when running some of the other peripherals simultaneously. If I have time I'll test the -RT patches as well and post up some numbers for this processor.