From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752710AbcFNT0j (ORCPT ); Tue, 14 Jun 2016 15:26:39 -0400 Received: from mail-by2on0106.outbound.protection.outlook.com ([207.46.100.106]:9088 "EHLO na01-by2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751801AbcFNT0i (ORCPT ); Tue, 14 Jun 2016 15:26:38 -0400 Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=waiman.long@hpe.com; Message-ID: <576056DB.5050701@hpe.com> Date: Tue, 14 Jun 2016 15:11:23 -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: Davidlohr Bueso CC: Peter Zijlstra , Ingo Molnar , , , , , , , , Jason Low , Dave Chinner , Scott J Norton , Douglas Hatch Subject: Re: [RFC PATCH-tip 2/6] locking/rwsem: Enable optional count-based spinning on reader References: <1465927959-39719-1-git-send-email-Waiman.Long@hpe.com> <1465927959-39719-3-git-send-email-Waiman.Long@hpe.com> <20160614182757.GA15903@linux-80c1.suse> In-Reply-To: <20160614182757.GA15903@linux-80c1.suse> Content-Type: text/plain; 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This aggressive spinning >> mode should only be used on rwsems where the readers are unlikely to >> go to sleep. > > Yikes, exposing this sort of thing makes me _very_ uneasy, not to mention > the ad-hoc nature and its easiness to mess up. I'm not really for > this, even > if it shows extraordinary performance boosts on benchmarks. > > Thanks, > Davidlohr I understand your concern. I will see if there is a way to autotune instead of using explicit enablement. Cheers, Longman From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Subject: Re: [RFC PATCH-tip 2/6] locking/rwsem: Enable optional count-based spinning on reader Date: Tue, 14 Jun 2016 15:11:23 -0400 Message-ID: <576056DB.5050701@hpe.com> References: <1465927959-39719-1-git-send-email-Waiman.Long@hpe.com> <1465927959-39719-3-git-send-email-Waiman.Long@hpe.com> <20160614182757.GA15903@linux-80c1.suse> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160614182757.GA15903@linux-80c1.suse> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com List-Archive: List-Post: To: Davidlohr Bueso Cc: linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, linux-ia64@vger.kernel.org, Scott J Norton , Peter Zijlstra , x86@kernel.org, linux-kernel@vger.kernel.org, xfs@oss.sgi.com, Ingo Molnar , linux-alpha@vger.kernel.org, Douglas Hatch , Jason Low List-ID: On 06/14/2016 02:27 PM, Davidlohr Bueso wrote: > On Tue, 14 Jun 2016, Waiman Long wrote: > >> This patch provides a way for the kernel code to designate specific >> rwsems to be more aggressive in term of optimistic spinning that the >> writers will continue to spin for some additional count-based time to >> see if it can get the lock before sleeping. This aggressive spinning >> mode should only be used on rwsems where the readers are unlikely to >> go to sleep. > > Yikes, exposing this sort of thing makes me _very_ uneasy, not to mention > the ad-hoc nature and its easiness to mess up. I'm not really for > this, even > if it shows extraordinary performance boosts on benchmarks. > > Thanks, > Davidlohr I understand your concern. I will see if there is a way to autotune instead of using explicit enablement. Cheers, Longman _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-by2on0107.outbound.protection.outlook.com ([207.46.100.107]:59296 "EHLO na01-by2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751364AbcFNTlp (ORCPT ); Tue, 14 Jun 2016 15:41:45 -0400 Message-ID: <576056DB.5050701@hpe.com> Date: Tue, 14 Jun 2016 15:11:23 -0400 From: Waiman Long MIME-Version: 1.0 Subject: Re: [RFC PATCH-tip 2/6] locking/rwsem: Enable optional count-based spinning on reader References: <1465927959-39719-1-git-send-email-Waiman.Long@hpe.com> <1465927959-39719-3-git-send-email-Waiman.Long@hpe.com> <20160614182757.GA15903@linux-80c1.suse> In-Reply-To: <20160614182757.GA15903@linux-80c1.suse> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Davidlohr Bueso Cc: Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, x86@kernel.org, linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, linux-s390@vger.kernel.org, linux-arch@vger.kernel.org, xfs@oss.sgi.com, Jason Low , Dave Chinner , Scott J Norton , Douglas Hatch Message-ID: <20160614191123.YAt4pFab4vn9miwlZC012ZrgNyPtQ1IClxBVI5rG-sk@z> On 06/14/2016 02:27 PM, Davidlohr Bueso wrote: > On Tue, 14 Jun 2016, Waiman Long wrote: > >> This patch provides a way for the kernel code to designate specific >> rwsems to be more aggressive in term of optimistic spinning that the >> writers will continue to spin for some additional count-based time to >> see if it can get the lock before sleeping. This aggressive spinning >> mode should only be used on rwsems where the readers are unlikely to >> go to sleep. > > Yikes, exposing this sort of thing makes me _very_ uneasy, not to mention > the ad-hoc nature and its easiness to mess up. I'm not really for > this, even > if it shows extraordinary performance boosts on benchmarks. > > Thanks, > Davidlohr I understand your concern. I will see if there is a way to autotune instead of using explicit enablement. Cheers, Longman From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Date: Tue, 14 Jun 2016 19:11:23 +0000 Subject: Re: [RFC PATCH-tip 2/6] locking/rwsem: Enable optional count-based spinning on reader Message-Id: <576056DB.5050701@hpe.com> List-Id: References: <1465927959-39719-1-git-send-email-Waiman.Long@hpe.com> <1465927959-39719-3-git-send-email-Waiman.Long@hpe.com> <20160614182757.GA15903@linux-80c1.suse> In-Reply-To: <20160614182757.GA15903@linux-80c1.suse> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Davidlohr Bueso Cc: Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, x86@kernel.org, linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, linux-s390@vger.kernel.org, linux-arch@vger.kernel.org, xfs@oss.sgi.com, Jason Low , Dave Chinner , Scott J Norton , Douglas Hatch On 06/14/2016 02:27 PM, Davidlohr Bueso wrote: > On Tue, 14 Jun 2016, Waiman Long wrote: > >> This patch provides a way for the kernel code to designate specific >> rwsems to be more aggressive in term of optimistic spinning that the >> writers will continue to spin for some additional count-based time to >> see if it can get the lock before sleeping. This aggressive spinning >> mode should only be used on rwsems where the readers are unlikely to >> go to sleep. > > Yikes, exposing this sort of thing makes me _very_ uneasy, not to mention > the ad-hoc nature and its easiness to mess up. I'm not really for > this, even > if it shows extraordinary performance boosts on benchmarks. > > Thanks, > Davidlohr I understand your concern. I will see if there is a way to autotune instead of using explicit enablement. Cheers, Longman