From mboxrd@z Thu Jan 1 00:00:00 1970 From: Davidlohr Bueso Subject: Re: [RFC PATCH-tip 2/6] locking/rwsem: Enable optional count-based spinning on reader Date: Tue, 14 Jun 2016 11:27:57 -0700 Message-ID: <20160614182757.GA15903@linux-80c1.suse> References: <1465927959-39719-1-git-send-email-Waiman.Long@hpe.com> <1465927959-39719-3-git-send-email-Waiman.Long@hpe.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Return-path: Content-Disposition: inline In-Reply-To: <1465927959-39719-3-git-send-email-Waiman.Long@hpe.com> Sender: linux-alpha-owner@vger.kernel.org List-Archive: List-Post: To: Waiman Long 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 List-ID: 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