From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E0F33C433DF for ; Fri, 3 Jul 2020 05:55:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B7F5520771 for ; Fri, 3 Jul 2020 05:55:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726110AbgGCFzE (ORCPT ); Fri, 3 Jul 2020 01:55:04 -0400 Received: from mga06.intel.com ([134.134.136.31]:18291 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725764AbgGCFzD (ORCPT ); Fri, 3 Jul 2020 01:55:03 -0400 IronPort-SDR: cyE/XyKNTNP02QGL9eZ++jUH7tQLOlY6uI8mJeKM04XHvpGhF1LIBNsRINWF3TZvVhyamJSLyJ +67QT3iWbIuw== X-IronPort-AV: E=McAfee;i="6000,8403,9670"; a="208614433" X-IronPort-AV: E=Sophos;i="5.75,307,1589266800"; d="scan'208";a="208614433" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Jul 2020 22:55:02 -0700 IronPort-SDR: 1/dfEGOro3OAp3tG2MJqrkY5IghHqv7u5uY+3ngl3gAohzd5F0aeqOqnBbBiejAoHWeqVvuGwh 8P6CBD5tp6tQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,307,1589266800"; d="scan'208";a="321718978" Received: from shao2-debian.sh.intel.com (HELO [10.239.13.3]) ([10.239.13.3]) by FMSMGA003.fm.intel.com with ESMTP; 02 Jul 2020 22:55:00 -0700 Subject: Re: [bpf] af7ec13833: will-it-scale.per_process_ops -2.5% regression To: Yonghong Song Cc: Alexei Starovoitov , Andrii Nakryiko , Martin KaFai Lau , LKML , lkp@lists.01.org References: <20200628085032.GT5535@shao2-debian> From: Rong Chen Message-ID: <1d98d1f0-fe84-6df7-f5bd-f4cb2cdb7f45@intel.com> Date: Fri, 3 Jul 2020 13:54:39 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/29/20 11:10 PM, Yonghong Song wrote: > > > On 6/28/20 1:50 AM, kernel test robot wrote: >> Greeting, >> >> FYI, we noticed a -2.5% regression of will-it-scale.per_process_ops >> due to commit: >> >> >> commit: af7ec13833619e17f03aa73a785a2f871da6d66b ("bpf: Add >> bpf_skc_to_tcp6_sock() helper") >> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master > > One of previous emails claims that >     commit: 492e639f0c222784e2e0f121966375f641c61b15 ("bpf: Add > bpf_seq_printf and bpf_seq_write helpers") > is reponsible for 2.5% improvement for will-it-scale.per_process_ops, > which I believe is false. > > This commit should not cause regression. > > Probably the variation of performance is caused by test environment > which you may want to investigate further to reduce false alarming. > Thanks! Hi Yonghong, It's a function align issue, the commit effects the align of functions which causes a little regression, we force to set -falign-functions=32 in KBUILD_CFLAGS and the regression is gone: diff --git a/Makefile b/Makefile index 70def4907036c..9746afa4edc21 100644 --- a/Makefile +++ b/Makefile @@ -476,7 +476,7 @@ LINUXINCLUDE    := \                 $(USERINCLUDE)  KBUILD_AFLAGS   := -D__ASSEMBLY__ -fno-PIE -KBUILD_CFLAGS   := -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs \ +KBUILD_CFLAGS   := -Wall -Wundef -falign-functions=32 -Werror=strict-prototypes -Wno-trigraphs \                    -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE \                    -Werror=implicit-function-declaration -Werror=implicit-int \                    -Wno-format-security \ Best Regards, Rong Chen > >> >> in testcase: will-it-scale >> on test machine: 192 threads Intel(R) Xeon(R) Platinum 9242 CPU @ >> 2.30GHz with 192G memory >> with following parameters: >> >>     nr_task: 16 >>     mode: process >>     test: mmap1 >>     cpufreq_governor: performance >>     ucode: 0x5002f01 >> >> test-description: Will It Scale takes a testcase and runs it from 1 >> through to n parallel copies to see if the testcase will scale. It >> builds both a process and threads based test in order to see any >> differences between the two. >> test-url: https://github.com/antonblanchard/will-it-scale >> >> >> >> If you fix the issue, kindly add following tag >> Reported-by: kernel test robot >> >> >> Details are as below: > [...]