Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267409AbUJOACF (ORCPT ); Thu, 14 Oct 2004 20:02:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268074AbUJOAB4 (ORCPT ); Thu, 14 Oct 2004 20:01:56 -0400 Received: from opersys.com ([64.40.108.71]:44302 "EHLO www.opersys.com") by vger.kernel.org with ESMTP id S267411AbUJNX7U (ORCPT ); Thu, 14 Oct 2004 19:59:20 -0400 Message-ID: <416F14B4.8070002@opersys.com> Date: Thu, 14 Oct 2004 20:07:16 -0400 From: Karim Yaghmour Reply-To: karim@opersys.com Organization: Opersys inc. User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 X-Accept-Language: en-us, en, fr, fr-be, fr-ca, fr-fr MIME-Version: 1.0 To: Ingo Molnar CC: linux-kernel@vger.kernel.org, Thomas Zanussi , Robert Wisniewski , Richard J Moore , Michel Dagenais Subject: Re: [patch] Real-Time Preemption, -VP-2.6.9-rc4-mm1-U0 References: <20041011215909.GA20686@elte.hu> <20041012091501.GA18562@elte.hu> <20041012123318.GA2102@elte.hu> <20041012195424.GA3961@elte.hu> <20041013061518.GA1083@elte.hu> <20041014002433.GA19399@elte.hu> <416F0071.3040304@opersys.com> <20041014234603.GA22964@elte.hu> In-Reply-To: <20041014234603.GA22964@elte.hu> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1087 Lines: 32 Ingo Molnar wrote: > i just added something ad-hoc. Yes, I understood as much. I'm suggesting it because a lot of people who need such ad-hoc functionality could easily be using relayfs. > I wanted it to be accurate across > interrupt entries. I have not looked at the relayfs locking but how does > it solve that? cmpxchg (basically: try reserve; if fail retry; else write), with per-cpu buffers. > Also, cli/sti makes it obviously SMP-safe and is pretty > cheap on all x86 CPUs. (Also, i didnt want to use preempt_disable/enable > because the tracer interacts with that code quite heavily.) No preempt_disable/enable found in the lockless logging in relayfs. Karim -- Author, Speaker, Developer, Consultant Pushing Embedded and Real-Time Linux Systems Beyond the Limits http://www.opersys.com || karim@opersys.com || 1-866-677-4546 - 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/