Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964946AbWHXPIj (ORCPT ); Thu, 24 Aug 2006 11:08:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964986AbWHXPIj (ORCPT ); Thu, 24 Aug 2006 11:08:39 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:3052 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S964946AbWHXPIi (ORCPT ); Thu, 24 Aug 2006 11:08:38 -0400 Date: Thu, 24 Aug 2006 17:00:26 +0200 From: Ingo Molnar To: Nick Piggin Cc: Arjan van de Ven , ego@in.ibm.com, rusty@rustcorp.com.au, torvalds@osdl.org, akpm@osdl.org, linux-kernel@vger.kernel.org, arjan@intel.linux.com, davej@redhat.com, dipankar@in.ibm.com, vatsa@in.ibm.com, ashok.raj@intel.com Subject: Re: [RFC][PATCH 4/4] Rename lock_cpu_hotplug/unlock_cpu_hotplug Message-ID: <20060824150026.GA14853@elte.hu> References: <20060824103417.GE2395@in.ibm.com> <1156417200.3014.54.camel@laptopd505.fenrus.org> <20060824140342.GI2395@in.ibm.com> <1156429015.3014.68.camel@laptopd505.fenrus.org> <44EDBDDE.7070203@yahoo.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <44EDBDDE.7070203@yahoo.com.au> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: -2.9 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.9 required=5.9 tests=ALL_TRUSTED,AWL,BAYES_50 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts 0.5 BAYES_50 BODY: Bayesian spam probability is 40 to 60% [score: 0.5000] -0.1 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 818 Lines: 19 * Nick Piggin wrote: > It really is just like a reentrant rw semaphore... I don't see the > point of the name change, but I guess we don't like reentrant locks so > calling it something else might go down better with Linus ;) what would fit best is a per-cpu scalable (on the read-side) self-reentrant rw mutex. We are doing cpu hotplug locking in things like fork or the slab code, while most boxes will do a CPU hotplug event only once in the kernel's lifetime (during bootup), so a classic global read-write lock is unjustified. 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/