From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264336AbTDKMF7 (for ); Fri, 11 Apr 2003 08:05:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264338AbTDKMF7 (for ); Fri, 11 Apr 2003 08:05:59 -0400 Received: from meg.hrz.tu-chemnitz.de ([134.109.132.57]:8405 "EHLO meg.hrz.tu-chemnitz.de") by vger.kernel.org with ESMTP id S264336AbTDKMF6 (for ); Fri, 11 Apr 2003 08:05:58 -0400 Date: Fri, 11 Apr 2003 11:27:28 +0200 From: Ingo Oeser To: george anzinger Cc: Keith Owens , linux-kernel@vger.kernel.org Subject: Re: 2.4.20 kernel/timer.c may incorrectly reenable interrupts Message-ID: <20030411112728.M626@nightmaster.csn.tu-chemnitz.de> References: <24294.1050043625@kao2.melbourne.sgi.com> <3E966BAA.804@mvista.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2i In-Reply-To: <3E966BAA.804@mvista.com>; from george@mvista.com on Fri, Apr 11, 2003 at 12:15:54AM -0700 X-Spam-Score: -32.5 (--------------------------------) X-Scanner: exiscan for exim4 (http://duncanthrax.net/exiscan/) *193xTQ-0002cx-00*NtjA9X/c/g6* Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 11, 2003 at 12:15:54AM -0700, george anzinger wrote: > As machines get faster and faster, it will be come more and more of a > burden to "stop the world" and sync with the interrupt system, which > is running at a much slower speed. This is what the cli / sti/ > restore flags causes. I saw one test where the time to do the cli was > as long as the run_timer_list code, for example. Maybe we could replace some cli/sti pairs with spinlocks? If it takes more time to cli/sti than to run the whole code section that will be protected by the spinlock, then it might be better to use that instead and block in the IRQ dispatch code. But I have no measures, how fast the spinlocks are in the non-/contention case Problems: - The total amount of CLI/STI doesn't matter, for spinlocks it does (they are not recursive) - spinlocks are usally not compiled in - Older CPUs may still benefit from cli/sti. What do you think? Regards Ingo Oeser -- Marketing ist die Kunst, Leuten Sachen zu verkaufen, die sie nicht brauchen, mit Geld, was sie nicht haben, um Leute zu beeindrucken, die sie nicht moegen.