Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268325AbUJTPl2 (ORCPT ); Wed, 20 Oct 2004 11:41:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268436AbUJTPlU (ORCPT ); Wed, 20 Oct 2004 11:41:20 -0400 Received: from viper.oldcity.dca.net ([216.158.38.4]:63879 "HELO viper.oldcity.dca.net") by vger.kernel.org with SMTP id S268368AbUJTPhi (ORCPT ); Wed, 20 Oct 2004 11:37:38 -0400 Subject: Re: [patch] Real-Time Preemption, -RT-2.6.9-rc4-mm1-U8 From: Lee Revell To: Ingo Molnar Cc: Florian Schmidt , linux-kernel , Rui Nuno Capela , Mark_H_Johnson@Raytheon.com, "K.R. Foley" , Bill Huey , Adam Heath , Thomas Gleixner , Michal Schmidt , Fernando Pablo Lopez-Lezcano In-Reply-To: <20041020141822.GA16965@elte.hu> References: <20041015102633.GA20132@elte.hu> <20041016153344.GA16766@elte.hu> <20041018145008.GA25707@elte.hu> <20041019124605.GA28896@elte.hu> <20041019180059.GA23113@elte.hu> <20041020094508.GA29080@elte.hu> <20041020145019.176826cb@mango.fruits.de> <20041020125500.GA8693@elte.hu> <20041020152507.3c167ca8@mango.fruits.de> <20041020162428.7c4c5f53@mango.fruits.de> <20041020141822.GA16965@elte.hu> Content-Type: text/plain Message-Id: <1098286655.1429.22.camel@krustophenia.net> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 Date: Wed, 20 Oct 2004 11:37:36 -0400 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1323 Lines: 34 On Wed, 2004-10-20 at 10:18, Ingo Molnar wrote: > note that the keyboard and USB interrupts are SCHED_OTHER by default, so > they could be delayed quite long depending on the workload. Why is this the default behavior? It seems like you would want all IRQ threads to be SCHED_FIFO by default. Otherwise it seems like the scheduler could decide to run a normal userspace process (like, say, X) while an IRQ thread is runnable. Is it really a good idea for IRQ threads to be subject to the whims of the scheduler? Also, on modern machines, this would effectively make all IRQ threads SCHED_OTHER because the USB port shares an interrupt with everything: 0: 36676353 XT-PIC timer 0/76353 1: 8759 XT-PIC i8042 5/8759 2: 0 XT-PIC cascade 0/0 8: 4 XT-PIC rtc 0/4 10: 0 XT-PIC uhci_hcd 0/0 11: 210713 XT-PIC uhci_hcd, eth0 0/10713 12: 0 XT-PIC uhci_hcd 0/0 15: 79277 XT-PIC ide1 0/79276 NMI: 0 ERR: 0 Lee - 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/