Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752082AbdHCXc2 (ORCPT ); Thu, 3 Aug 2017 19:32:28 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:42126 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751897AbdHCXc0 (ORCPT ); Thu, 3 Aug 2017 19:32:26 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Date: Thu, 03 Aug 2017 16:32:25 -0700 From: Vikram Mulukutla To: qiaozhou Cc: Will Deacon , 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: References: <3d2459c7-defd-a47e-6cea-007c10cecaac@asrmicro.com> <20170728092831.GA24839@arm.com> <2aa9684cf9c889ee9fdc8550b4388af6@codeaurora.org> <1c951f01-c450-d21b-13e9-6a32eb509d94@asrmicro.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: 1957 Lines: 58 Hi Qiao, On 2017-08-01 00:37, qiaozhou wrote: > On 2017年07月31日 19:20, qiaozhou wrote: >> >> >>> ===================================================== >>> Also apply Vikram's patch and have a test. > > cpu2: a53, 832MHz, cpu7: a73, 1.75Hz > Without cpu_relax bodging patch > ===================================================== > cpu2 time | cpu2 counter | cpu7 time | cpu7 counter | > ==========|==============|===========|==============| > 16505| 5243| 2| 12487322| > 16494| 5619| 1| 12013291| > 16498| 5276| 2| 11706824| > 16494| 7123| 1| 12532355| > 16470| 7208| 2| 11784617| > ===================================================== > > cpu2: a53, 832MHz, cpu7: a73, 1.75Hz > With cpu_relax bodging patch: > ===================================================== > cpu2 time | cpu2 counter | cpu7 time | cpu7 counter | > ==========|==============|===========|==============| > 3991| 140714| 1| 11430528| > 4018| 144371| 1| 11430528| > 4034| 143250| 1| 11427011| > 4330| 147345| 1| 11423583| > 4752| 138273| 1| 11433241| > ===================================================== > > It has some improvements, but not so good as Vikram's data. The big > core still has much more chance to acquire lock. >>> >>> Thanks, >>> Vikram >>> Thanks for your data! I'll check on one of our other platforms to see if I see similar behavior. This may have something to do with the event-stream on your platform or the A53 revision as Sudeep pointed out here [1] - something to check I suppose... Thanks, Vikram [1] - https://lkml.org/lkml/2016/11/21/458 -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project