Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269200AbUJQRKr (ORCPT ); Sun, 17 Oct 2004 13:10:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269205AbUJQRKr (ORCPT ); Sun, 17 Oct 2004 13:10:47 -0400 Received: from mx2.elte.hu ([157.181.151.9]:26254 "EHLO mx2.elte.hu") by vger.kernel.org with ESMTP id S269200AbUJQRKp (ORCPT ); Sun, 17 Oct 2004 13:10:45 -0400 Date: Sun, 17 Oct 2004 19:12:09 +0200 From: Ingo Molnar To: Dipankar Sarma Cc: Sven Dietrich , Daniel Walker , Andrew Morton , linux-kernel@vger.kernel.org, abatyrshin@ru.mvista.com, amakarov@ru.mvista.com, emints@ru.mvista.com, ext-rt-dev@mvista.com, hzhang@ch.mvista.com, yyang@ch.mvista.com, "Witold. Jaworski@Unibw-Muenchen. De" , arnd.heursch@unibw-muenchen.de Subject: Re: [ANNOUNCE] Linux 2.6 Real Time Kernel Message-ID: <20041017171209.GA27341@elte.hu> References: <20041011215420.GA19796@elte.hu> <20041012055029.GB1479@elte.hu> <20041014050905.GA6927@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041014050905.GA6927@in.ibm.com> User-Agent: Mutt/1.4.1i X-ELTE-SpamVersion: MailScanner 4.31.6-itk1 (ELTE 1.2) SpamAssassin 2.63 ClamAV 0.73 X-ELTE-VirusStatus: clean X-ELTE-SpamCheck: no X-ELTE-SpamCheck-Details: score=-4.9, required 5.9, autolearn=not spam, BAYES_00 -4.90 X-ELTE-SpamLevel: X-ELTE-SpamScore: -4 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 950 Lines: 24 * Dipankar Sarma wrote: > It seems that way to me too. Long ago I implemented preemptible RCU, > but did not follow it through because I believed it was not a good > idea. The original patch is here : > > http://www.uwsg.iu.edu/hypermail/linux/kernel/0205.1/0026.html > > This allows read-side critical sections of RCU to be preempted. It > will take a bit of work to re-use it in RCU as of now, but I don't > think it makes sense to do so. My primary concern is DoS/OOM situation > due to preempted tasks holding up RCU. the DoS/OOM problems are serious i believe. Preemptible RCU in that sense is 'RCU with no guarantee of progress', which sounds bad from a design POV. Ingo - 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/