From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757808AbcJQXVj (ORCPT ); Mon, 17 Oct 2016 19:21:39 -0400 Received: from mail-cys01nam02on0133.outbound.protection.outlook.com ([104.47.37.133]:19872 "EHLO NAM02-CY1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754925AbcJQXVi (ORCPT ); Mon, 17 Oct 2016 19:21:38 -0400 Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=waiman.long@hpe.com; Message-ID: <58055CF8.2060806@hpe.com> Date: Mon, 17 Oct 2016 19:21:28 -0400 From: Waiman Long User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.12) Gecko/20130109 Thunderbird/10.0.12 MIME-Version: 1.0 To: Peter Zijlstra CC: Linus Torvalds , Jason Low , Ding Tianhong , Thomas Gleixner , Will Deacon , Ingo Molnar , Imre Deak , Linux Kernel Mailing List , Davidlohr Bueso , Tim Chen , Terry Rudd , "Paul E. McKenney" , Jason Low , Chris Wilson , Daniel Vetter Subject: Re: [PATCH -v4 8/8] locking/mutex: Enable optimistic spinning of woken waiter References: <20161007145243.361481786@infradead.org> <20161007150211.416377482@infradead.org> In-Reply-To: <20161007150211.416377482@infradead.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [72.71.243.218] X-ClientProxiedBy: BY1PR13CA0035.namprd13.prod.outlook.com (10.162.107.173) To DF4PR84MB0313.NAMPRD84.PROD.OUTLOOK.COM (10.162.193.27) X-MS-Office365-Filtering-Correlation-Id: 76d9cdbe-5fc5-47ad-961d-08d3f6e456fd X-Microsoft-Exchange-Diagnostics: 1;DF4PR84MB0313;2:fnpNKsn3iadLFOiHS8V5l+4KjDti/6l9S+6SKKtd5HhVxNmCADiRobq9oUklzzHLwlhyLMst5cM1Zq7wGXLD2HGVSFvyKW/l9uTsDHX3q+Eh43ZAsQPB07eNKdRvVzvgeXamJi+R+GojPYM/XBXLTPpmZsyxML8yFRfS5FIRQdM91oEp5MB68xcZEig156eHC3s3+xez4Bk11EeOAG//HQ==;3:xb49qa4bpvZXs4UzGt8JzFXLm6mJx6fJyG8+qQ9ZooKN6acEa1jF7pVbOQ+KtiuNB/t+CyeL6eEYCUG6vLgNNCs4QrE1Vi16O9A6I1yE/0DJLc+tkGfQcEDusuW9pw8zZ/rdEVO0SadnkyYNZaAL/g== X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:DF4PR84MB0313; 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> > if (__mutex_trylock(lock, false) || > - mutex_optimistic_spin(lock, ww_ctx, use_ww_ctx)) { > + mutex_optimistic_spin(lock, ww_ctx, use_ww_ctx, false)) { > /* got the lock, yay! */ > lock_acquired(&lock->dep_map, ip); > if (use_ww_ctx) > @@ -669,7 +699,8 @@ __mutex_lock_common(struct mutex *lock, > * state back to RUNNING and fall through the next schedule(), > * or we must see its unlock and acquire. > */ > - if (__mutex_trylock(lock, first)) > + if ((first&& mutex_optimistic_spin(lock, ww_ctx, use_ww_ctx, true)) || > + __mutex_trylock(lock, first)) Do we need a __mutex_trylock() here? mutex_optimistic_spin() will do the trylock and we have one at the top of the loop. Cheers, Longman