Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751145AbWHXLcN (ORCPT ); Thu, 24 Aug 2006 07:32:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751152AbWHXLcN (ORCPT ); Thu, 24 Aug 2006 07:32:13 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:6854 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S1751145AbWHXLcM (ORCPT ); Thu, 24 Aug 2006 07:32:12 -0400 Date: Thu, 24 Aug 2006 13:24:22 +0200 From: Ingo Molnar To: Gautham R Shenoy Cc: rusty@rustcorp.com.au, torvalds@osdl.org, akpm@osdl.org, linux-kernel@vger.kernel.org, arjan@linux.intel.com, davej@redhat.com, vatsa@in.ibm.com, dipankar@in.ibm.com, ashok.raj@intel.com Subject: Re: [RFC][PATCH 0/4] Redesign cpu_hotplug locking. Message-ID: <20060824112422.GA21121@elte.hu> References: <20060824102618.GA2395@in.ibm.com> <20060824103412.GA14002@elte.hu> <20060824112749.GG2395@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060824112749.GG2395@in.ibm.com> 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: 1332 Lines: 30 * Gautham R Shenoy wrote: > On Thu, Aug 24, 2006 at 12:34:12PM +0200, Ingo Molnar wrote: > > Please add the appropriate lock_acquire()/lock_release() calls into the > > new sleeping semaphore type. Just use the parameters that rwlocks use: > > > > #define rwlock_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, i) > > #define rwlock_acquire_read(l, s, t, i) lock_acquire(l, s, t, 2, 2, i) > > > and lockdep will allow recursive read-locking. You'll also need a > > lockdep_init_map() call to register the lock with lockdep. Then your > > locking scheme will be fully checked by lockdep too. (with your current > > code the new lock type is not added to the lock dependency graph(s)) > > I'm on it. :) you'll also need to add a dep_map to the cpu_hotplug structure itself. and i think this extension of lockdep to the new lock type will be invariant with the per-cpu optimizations i suggested in the previous mail: because it's only the scalability of cpu_hotplug_lock() that will improve [dramatically], its locking semantics wont. 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/