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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E92F1C43334 for ; Mon, 13 Jun 2022 02:09:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235664AbiFMCJt (ORCPT ); Sun, 12 Jun 2022 22:09:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54896 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231376AbiFMCJs (ORCPT ); Sun, 12 Jun 2022 22:09:48 -0400 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2DCBC21250; Sun, 12 Jun 2022 19:09:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1655086188; x=1686622188; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=+fem5FyudAz01p+w/Af/9mmPzXNj8Wp0IAnkI0tnZHI=; b=UuZBV9GPahHME/ZhZLAoX/3R0Qmgi9pphWTMAe1Jke9hd7wLXC+9Zdgm B76F/osL4vRXkqnBY2ma3dc/WK8qOabL2pSjSPLzEMY0Qu6FjAvFw2Ch2 dW+EI/AOiLzEIGrwnOmlK53qk/zO5l9seS4TFND1T8lY5q+z61aqWFMjs /PTAd2yOOWzKi/PRL74SPjVRvZLayD1YAMO/VBdw7QTpwJ0AqeifTQilv 1DDyDlkYcG4XOua70QDWH2wLlZRq8kAcOfN4ZI/a+0zMSKtRAbaTD4blX kFx1fN71ZD1pZlObBULmCQC/+G/d9SwYIl202WfBXHMUDPy1CUgIvvGIe Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10376"; a="303526704" X-IronPort-AV: E=Sophos;i="5.91,296,1647327600"; d="scan'208";a="303526704" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jun 2022 19:09:47 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.91,296,1647327600"; d="scan'208";a="587525050" Received: from shbuild999.sh.intel.com (HELO localhost) ([10.239.146.138]) by fmsmga007.fm.intel.com with ESMTP; 12 Jun 2022 19:09:43 -0700 Date: Mon, 13 Jun 2022 10:09:43 +0800 From: Feng Tang To: Willy Tarreau , Moshe Kol , fengwei.yin@intel.com Cc: Moshe Kol , kernel test robot , Jakub Kicinski , Yossi Gilad , Amit Klein , Eric Dumazet , LKML , netdev@vger.kernel.org, lkp@lists.01.org, lkp@intel.com, ying.huang@intel.com, zhengjun.xing@linux.intel.com, fengwei.yin@intel.com Subject: Re: [tcp] e926147618: stress-ng.icmp-flood.ops_per_sec -8.7% regression Message-ID: <20220613020943.GD75244@shbuild999.sh.intel.com> References: <20220608060802.GA22428@xsang-OptiPlex-9020> <20220608064822.GC7547@1wt.eu> <20220608073441.GE7547@1wt.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220608073441.GE7547@1wt.eu> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi, On Wed, Jun 08, 2022 at 09:34:41AM +0200, Willy Tarreau wrote: > On Wed, Jun 08, 2022 at 10:26:12AM +0300, Moshe Kol wrote: > > Hmm, How is the ICMP flood stress test related to TCP connections? > > To me it's not directly related, unless the test pre-establishes many > connections, or is affected in a way or another by a larger memory > allocation of this part. Fengwei and I discussed and thought this could be a data alignment related case, that one module's data alignment change affects other modules' alignment, and we had a patch for detecting similar cases [1] After some debugging, this could be related with the bss section alignment changes, that if we forced all module's bss section to be 4KB aligned, then the stress-ng icmp-flood case will have almost no performance difference for the 2 commits: 10025135 +0.8% 10105711 ± 2% stress-ng.icmp-flood.ops_per_sec The debug patch is: diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index 7fda7f27e7620..7eb626b98620c 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -378,7 +378,9 @@ SECTIONS /* BSS */ . = ALIGN(PAGE_SIZE); - .bss : AT(ADDR(.bss) - LOAD_OFFSET) { + .bss : AT(ADDR(.bss) - LOAD_OFFSET) + SUBALIGN(PAGE_SIZE) + { __bss_start = .; *(.bss..page_aligned) . = ALIGN(PAGE_SIZE); The 'table_perturb[]' used to be in bss section, and with the commit of moving it to runtime allocation, other data structures following it in the .bss section will get affected accordingly. Thanks, Feng > Willy