From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755057Ab3BRQsQ (ORCPT ); Mon, 18 Feb 2013 11:48:16 -0500 Received: from e28smtp07.in.ibm.com ([122.248.162.7]:60548 "EHLO e28smtp07.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752226Ab3BRQsM (ORCPT ); Mon, 18 Feb 2013 11:48:12 -0500 Message-ID: <51225ACD.3080100@linux.vnet.ibm.com> Date: Mon, 18 Feb 2013 22:16:05 +0530 From: "Srivatsa S. Bhat" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120828 Thunderbird/15.0 MIME-Version: 1.0 To: Steven Rostedt CC: Michel Lespinasse , tglx@linutronix.de, peterz@infradead.org, tj@kernel.org, oleg@redhat.com, paulmck@linux.vnet.ibm.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org, wangyun@linux.vnet.ibm.com, xiaoguangrong@linux.vnet.ibm.com, rjw@sisk.pl, sbw@mit.edu, fweisbec@gmail.com, linux@arm.linux.org.uk, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, vincent.guittot@linaro.org Subject: Re: [PATCH v6 04/46] percpu_rwlock: Implement the core design of Per-CPU Reader-Writer Locks References: <20130218123714.26245.61816.stgit@srivatsabhat.in.ibm.com> <20130218123856.26245.46705.stgit@srivatsabhat.in.ibm.com> <5122551E.1080703@linux.vnet.ibm.com> <1361205087.23152.159.camel@gandalf.local.home> In-Reply-To: <1361205087.23152.159.camel@gandalf.local.home> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13021816-8878-0000-0000-000005F06EBF Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/18/2013 10:01 PM, Steven Rostedt wrote: > On Mon, 2013-02-18 at 21:51 +0530, Srivatsa S. Bhat wrote: >> Hi Michel, > >> Yes.. I don't think we can avoid that. Moreover, since we _want_ unfair >> reader/writer semantics to allow flexible locking rules and guarantee >> deadlock-safety, having a recursive reader side is not even an issue, IMHO. > > Recursive unfair reader lock may guarantee deadlock-safety, but > remember, it adds a higher probability of live-locking the write_lock. > Which is another argument to keep this separate to cpu hotplug only. > True. Regards, Srivatsa S. Bhat From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28smtp02.in.ibm.com (e28smtp02.in.ibm.com [122.248.162.2]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e28smtp02.in.ibm.com", Issuer "GeoTrust SSL CA" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 4E39B2C0092 for ; Tue, 19 Feb 2013 03:48:11 +1100 (EST) Received: from /spool/local by e28smtp02.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 18 Feb 2013 22:15:02 +0530 Received: from d28relay02.in.ibm.com (d28relay02.in.ibm.com [9.184.220.59]) by d28dlp01.in.ibm.com (Postfix) with ESMTP id A8C34E0054 for ; Mon, 18 Feb 2013 22:19:01 +0530 (IST) Received: from d28av01.in.ibm.com (d28av01.in.ibm.com [9.184.220.63]) by d28relay02.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r1IGm3fj31785088 for ; Mon, 18 Feb 2013 22:18:03 +0530 Received: from d28av01.in.ibm.com (loopback [127.0.0.1]) by d28av01.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r1IGm3FG029123 for ; Mon, 18 Feb 2013 16:48:05 GMT Message-ID: <51225ACD.3080100@linux.vnet.ibm.com> Date: Mon, 18 Feb 2013 22:16:05 +0530 From: "Srivatsa S. Bhat" MIME-Version: 1.0 To: Steven Rostedt Subject: Re: [PATCH v6 04/46] percpu_rwlock: Implement the core design of Per-CPU Reader-Writer Locks References: <20130218123714.26245.61816.stgit@srivatsabhat.in.ibm.com> <20130218123856.26245.46705.stgit@srivatsabhat.in.ibm.com> <5122551E.1080703@linux.vnet.ibm.com> <1361205087.23152.159.camel@gandalf.local.home> In-Reply-To: <1361205087.23152.159.camel@gandalf.local.home> Content-Type: text/plain; charset=ISO-8859-15 Cc: linux-doc@vger.kernel.org, peterz@infradead.org, fweisbec@gmail.com, linux-kernel@vger.kernel.org, Michel Lespinasse , mingo@kernel.org, linux-arch@vger.kernel.org, linux@arm.linux.org.uk, xiaoguangrong@linux.vnet.ibm.com, wangyun@linux.vnet.ibm.com, paulmck@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, rusty@rustcorp.com.au, rjw@sisk.pl, namhyung@kernel.org, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org, oleg@redhat.com, vincent.guittot@linaro.org, sbw@mit.edu, tj@kernel.org, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 02/18/2013 10:01 PM, Steven Rostedt wrote: > On Mon, 2013-02-18 at 21:51 +0530, Srivatsa S. Bhat wrote: >> Hi Michel, > >> Yes.. I don't think we can avoid that. Moreover, since we _want_ unfair >> reader/writer semantics to allow flexible locking rules and guarantee >> deadlock-safety, having a recursive reader side is not even an issue, IMHO. > > Recursive unfair reader lock may guarantee deadlock-safety, but > remember, it adds a higher probability of live-locking the write_lock. > Which is another argument to keep this separate to cpu hotplug only. > True. Regards, Srivatsa S. Bhat From mboxrd@z Thu Jan 1 00:00:00 1970 From: srivatsa.bhat@linux.vnet.ibm.com (Srivatsa S. Bhat) Date: Mon, 18 Feb 2013 22:16:05 +0530 Subject: [PATCH v6 04/46] percpu_rwlock: Implement the core design of Per-CPU Reader-Writer Locks In-Reply-To: <1361205087.23152.159.camel@gandalf.local.home> References: <20130218123714.26245.61816.stgit@srivatsabhat.in.ibm.com> <20130218123856.26245.46705.stgit@srivatsabhat.in.ibm.com> <5122551E.1080703@linux.vnet.ibm.com> <1361205087.23152.159.camel@gandalf.local.home> Message-ID: <51225ACD.3080100@linux.vnet.ibm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 02/18/2013 10:01 PM, Steven Rostedt wrote: > On Mon, 2013-02-18 at 21:51 +0530, Srivatsa S. Bhat wrote: >> Hi Michel, > >> Yes.. I don't think we can avoid that. Moreover, since we _want_ unfair >> reader/writer semantics to allow flexible locking rules and guarantee >> deadlock-safety, having a recursive reader side is not even an issue, IMHO. > > Recursive unfair reader lock may guarantee deadlock-safety, but > remember, it adds a higher probability of live-locking the write_lock. > Which is another argument to keep this separate to cpu hotplug only. > True. Regards, Srivatsa S. Bhat