Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752491AbZI1HYB (ORCPT ); Mon, 28 Sep 2009 03:24:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751797AbZI1HYA (ORCPT ); Mon, 28 Sep 2009 03:24:00 -0400 Received: from ns2.intersolute.de ([193.110.43.67]:55359 "EHLO ns2.intersolute.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751136AbZI1HYA (ORCPT ); Mon, 28 Sep 2009 03:24:00 -0400 X-Greylist: delayed 780 seconds by postgrey-1.27 at vger.kernel.org; Mon, 28 Sep 2009 03:23:59 EDT Message-ID: <4AC06187.2050806@lumino.de> Date: Mon, 28 Sep 2009 09:11:03 +0200 From: Michael Schnell User-Agent: Thunderbird 2.0.0.23 (X11/20090817) MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Subject: Re: [RFC] Userspace RCU: (ab)using futexes to save cpu cycles and energy References: <20090923174820.GA12827@Krystal> <4ABA631A.8030306@nortel.com> <20090923190337.GA16983@Krystal> <20090923223204.GA2921@Krystal> <4ABAAB4F.2060905@nortel.com> <20090923232855.GB9621@Krystal> In-Reply-To: <20090923232855.GB9621@Krystal> X-Enigmail-Version: 0.95.7 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 730 Lines: 19 Mathieu Desnoyers wrote: > > The mutex code (and usual futex users) use futex to implement mutual > exclusion. My goal is to send a wakeup signal to a thread waiting for > work to perform when adding such work. But without any mutual exclusion. Why is that different ? if you use a normal FUTEX like pthread_mutex_...() and have the thread block right at the start (by blocking the *UTEX before creating the thread). Now you can wake the thread by unblocking the *UTEX. -Michael -- 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/