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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 6C3BEC35671 for ; Mon, 24 Feb 2020 13:20:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 479F320828 for ; Mon, 24 Feb 2020 13:20:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727510AbgBXNUV (ORCPT ); Mon, 24 Feb 2020 08:20:21 -0500 Received: from mga11.intel.com ([192.55.52.93]:3141 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727329AbgBXNUU (ORCPT ); Mon, 24 Feb 2020 08:20:20 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Feb 2020 05:20:19 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,480,1574150400"; d="scan'208";a="260339378" Received: from shbuild999.sh.intel.com (HELO localhost) ([10.239.147.113]) by fmsmga004.fm.intel.com with ESMTP; 24 Feb 2020 05:20:14 -0800 Date: Mon, 24 Feb 2020 21:20:14 +0800 From: Feng Tang To: Linus Torvalds , ying.huang@intel.com Cc: Jiri Olsa , Peter Zijlstra , kernel test robot , Ingo Molnar , Vince Weaver , Jiri Olsa , Alexander Shishkin , Arnaldo Carvalho de Melo , Arnaldo Carvalho de Melo , "Naveen N. Rao" , Ravi Bangoria , Stephane Eranian , Thomas Gleixner , LKML , lkp@lists.01.org, andi.kleen@intel.com, "Huang, Ying" Subject: Re: [LKP] Re: [perf/x86] 81ec3f3c4c: will-it-scale.per_process_ops -5.5% regression Message-ID: <20200224132014.GA63607@shbuild999.sh.intel.com> References: <20200205123216.GO12867@shao2-debian> <20200205125804.GM14879@hirez.programming.kicks-ass.net> <20200221080325.GA67807@shbuild999.sh.intel.com> <20200221132048.GE652992@krava> <20200223141147.GA53531@shbuild999.sh.intel.com> <20200224003301.GA5061@shbuild999.sh.intel.com> <20200224021915.GC5061@shbuild999.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200224021915.GC5061@shbuild999.sh.intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 24, 2020 at 10:19:15AM +0800, Feng Tang wrote: > > > > > No, it's not the biggest, I tried another machine 'Xeon Phi(TM) CPU 7295', > > > which has 72C/288T, and the regression is not seen. This is the part > > > confusing me :) > > > > Hmm. > > > > Humor me - what happens if you turn off SMT on that Cascade Lake > > system? Maybe it's about the thread ID bit in the L1? Although again, > > I'd have expected things to get _worse_ if it's the two fields that > > are now in the same cachline thanks to alignment. > > I'll try it and report back. I added "nosmt=force" on the 2S 4 nodes 96C/192T machine, and tested both 96 and 192 processes, and the regression still exists. Also for Ying's suggestion about separate 'sigpending' to another cache line than '__refcount', it can not heal the regression either. Thanks, Feng From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============0127473572941514430==" MIME-Version: 1.0 From: Feng Tang To: lkp@lists.01.org Subject: Re: [perf/x86] 81ec3f3c4c: will-it-scale.per_process_ops -5.5% regression Date: Mon, 24 Feb 2020 21:20:14 +0800 Message-ID: <20200224132014.GA63607@shbuild999.sh.intel.com> In-Reply-To: <20200224021915.GC5061@shbuild999.sh.intel.com> List-Id: --===============0127473572941514430== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable On Mon, Feb 24, 2020 at 10:19:15AM +0800, Feng Tang wrote: > > = > > > No, it's not the biggest, I tried another machine 'Xeon Phi(TM) CPU 7= 295', > > > which has 72C/288T, and the regression is not seen. This is the part > > > confusing me :) > > = > > Hmm. > > = > > Humor me - what happens if you turn off SMT on that Cascade Lake > > system? Maybe it's about the thread ID bit in the L1? Although again, > > I'd have expected things to get _worse_ if it's the two fields that > > are now in the same cachline thanks to alignment. > = > I'll try it and report back. I added "nosmt=3Dforce" on the 2S 4 nodes 96C/192T machine, and tested both 96 and 192 processes, and the regression still exists. Also for Ying's suggestion about separate 'sigpending' to another cache line than '__refcount', it can not heal the regression either. Thanks, Feng --===============0127473572941514430==--