Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267856AbUJLVYu (ORCPT ); Tue, 12 Oct 2004 17:24:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267860AbUJLVYu (ORCPT ); Tue, 12 Oct 2004 17:24:50 -0400 Received: from smtp.Lynuxworks.com ([207.21.185.24]:62991 "EHLO smtp.lynuxworks.com") by vger.kernel.org with ESMTP id S267856AbUJLVYg (ORCPT ); Tue, 12 Oct 2004 17:24:36 -0400 Date: Tue, 12 Oct 2004 14:24:08 -0700 To: Bill Huey Cc: Thomas Gleixner , dwalker@mvista.com, Ingo Molnar , Andrew Morton , amakarov@ru.mvista.com, ext-rt-dev@mvista.com, LKML , "Bill Huey (hui)" Subject: Re: [Ext-rt-dev] Re: [ANNOUNCE] Linux 2.6 Real Time Kernel Message-ID: <20041012212408.GA28707@nietzsche.lynx.com> References: <41677E4D.1030403@mvista.com> <20041010084633.GA13391@elte.hu> <1097437314.17309.136.camel@dhcp153.mvista.com> <20041010142000.667ec673.akpm@osdl.org> <20041010215906.GA19497@elte.hu> <1097517191.28173.1.camel@dhcp153.mvista.com> <20041011204959.GB16366@elte.hu> <1097607049.9548.108.camel@dhcp153.mvista.com> <1097610393.19549.69.camel@thomas> <20041012211201.GA28590@nietzsche.lynx.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041012211201.GA28590@nietzsche.lynx.com> User-Agent: Mutt/1.5.6+20040907i From: Bill Huey (hui) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1299 Lines: 28 On Tue, Oct 12, 2004 at 02:12:01PM -0700, Bill Huey wrote: > On Tue, Oct 12, 2004 at 09:46:34PM +0200, Thomas Gleixner wrote: > > enter_critical_section(TYPE, &var, &flags, whatever); > > leave_critical_section(TYPE, &var, flags, whatever); > > FreeBSD uses these things, but it they create severe pipeline stalls > since they toggle interrupt flags on entry and exit. The current scheme > in Linux with preempt_count use to be a curse when I was working on an > equivalent implementation of there stuff at: > > http://mmlinux.sf.net Duh, I didn't finish the sentence. I meant this method above is nasty filled with pipeline stalls. Don't know if that's what were saying, but non-preemptable critical sections denoted by preempt_count must have some kind of conceptual overlap with local_irq* functions. I use to curse the seperation of the two since it made my own conception irregular, but I have come to the conclusion that using relatively something light weight like preempt_count() for that functionality instead. That's what I meant. :) bill - 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/