Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753577AbaA0MYE (ORCPT ); Mon, 27 Jan 2014 07:24:04 -0500 Received: from mga01.intel.com ([192.55.52.88]:16525 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751275AbaA0MYB (ORCPT ); Mon, 27 Jan 2014 07:24:01 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.95,728,1384329600"; d="scan'208";a="465293383" Date: Mon, 27 Jan 2014 20:23:58 +0800 From: Fengguang Wu To: Ming Lei Cc: LKML , Hugh Dickins Subject: Re: [percpu_counter] 74e72f894: -47.6% aim7 jobs-per-min Message-ID: <20140127122358.GA8166@localhost> References: <20140117102020.GA8751@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Ming Lei, On Fri, Jan 17, 2014 at 06:56:24PM +0800, Ming Lei wrote: > Hi Fengguang, > > On Fri, Jan 17, 2014 at 6:20 PM, Fengguang Wu wrote: > > Ming Lei, > > > > We noticed that commit 74e72f894 ("lib/percpu_counter.c: fix > > __percpu_counter_add()") introduces -47.6% regression in aim7 brk_test > > on a 2S SNB server. Comparing to its parent commit: > > The commit has a bug, could you apply Hugh's patch[1] to test if > the regression can be fixed? > > If the performance regression is still there, it may be caused by bad > performance of this_cpu_add(), then I suggest you to test the patch[2] > too without enabling lockdep. > > > [1], http://marc.info/?t=138991497900001&r=1&w=2 Hugh's patch is enough to fix the kernel oops and performance regressions: 74e72f894d56eb9 0ddc13035a9b3679a0e1a2cec --------------- ------------------------- 1 ~ 0% -100.0% 0 vpx/micro/xfstests/4HDD-ext4-generic-slow2 1 ~ 0% -100.0% 0 TOTAL dmesg.This_should_not_happen_Data_will_be_lost 74e72f894d56eb9 0ddc13035a9b3679a0e1a2cec --------------- ------------------------- 71965 ~ 0% +90.4% 137038 ~ 0% lkp-snb01/micro/aim7/brk_test 71965 ~ 0% +90.4% 137038 ~ 0% TOTAL aim7.2000.jobs-per-min In fact it turns regression to noticeable performance increase. :) Thanks, Fengguang > [2], http://marc.info/?l=linux-kernel&m=138909074202090&w=2 > > Thanks, > -- > Ming Lei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/