Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752421AbdHCXZP (ORCPT ); Thu, 3 Aug 2017 19:25:15 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:34648 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752369AbdHCXZN (ORCPT ); Thu, 3 Aug 2017 19:25:13 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Thu, 03 Aug 2017 16:25:12 -0700 From: Vikram Mulukutla To: Will Deacon Cc: qiaozhou , Thomas Gleixner , John Stultz , sboyd@codeaurora.org, LKML , Wang Wilbur , Marc Zyngier , Peter Zijlstra , linux-kernel-owner@vger.kernel.org, sudeep.holla@arm.com Subject: Re: [Question]: try to fix contention between expire_timers and try_to_del_timer_sync In-Reply-To: <20170731131321.GB1737@arm.com> References: <3d2459c7-defd-a47e-6cea-007c10cecaac@asrmicro.com> <20170728092831.GA24839@arm.com> <2aa9684cf9c889ee9fdc8550b4388af6@codeaurora.org> <20170731131321.GB1737@arm.com> Message-ID: User-Agent: Roundcube Webmail/1.2.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 974 Lines: 34 Hi Will, On 2017-07-31 06:13, Will Deacon wrote: > Hi Vikram, > > On Fri, Jul 28, 2017 at 12:09:38PM -0700, Vikram Mulukutla wrote: >> On 2017-07-28 02:28, Will Deacon wrote: >> >On Thu, Jul 27, 2017 at 06:10:34PM -0700, Vikram Mulukutla wrote: >> > >> This does seem to help. Here's some data after 5 runs with and without >> the >> patch. > > Blimey, that does seem to make a difference. Shame it's so ugly! Would > you > be able to experiment with other values for CPU_RELAX_WFE_THRESHOLD? I > had > it set to 10000 in the diff I posted, but that might be higher than > optimal. > It would be interested to see if it correlates with num_possible_cpus() > for the highly contended case. > > Will Sorry for the late response - I should hopefully have some more data with different thresholds before the week is finished or on Monday. Thanks, Vikram -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project