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=-5.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 B4A29C43331 for ; Sat, 28 Mar 2020 22:19:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 826DF2074A for ; Sat, 28 Mar 2020 22:19:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="jf5XJT25" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727773AbgC1WTb (ORCPT ); Sat, 28 Mar 2020 18:19:31 -0400 Received: from mail-pg1-f194.google.com ([209.85.215.194]:38337 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727115AbgC1WTa (ORCPT ); Sat, 28 Mar 2020 18:19:30 -0400 Received: by mail-pg1-f194.google.com with SMTP id x7so6651237pgh.5 for ; Sat, 28 Mar 2020 15:19:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=co2N4bkvAOJAUXCk/vC0UWvLXVTotTW2AO2YGPmDkQg=; b=jf5XJT25fVNwQA+I/A1whuGeDvFPM4+wyvi/iO9+vImp8u3YMrI49UHciUb0rE8Czj aGoG3ghm/Qhhq9oW8xnJZmaXO28xovjK/MOvqk3a4GD+RPDlSKdaK+ZtTJXmxv2icxut SDex7XpenXHpKKRJq7Z6yKwbKl3JC3KGfChE0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=co2N4bkvAOJAUXCk/vC0UWvLXVTotTW2AO2YGPmDkQg=; b=qFc+ISM95T9KVjrRm+P1Otpox45ZVBuHoKsA548D8NvjPNTWApp9zLEf9ALTTSxai7 7E4VAAp12t/sj4Ky9eIcxtL8Vbw4rgDVDNYSGQfA8XNhUkoL62gu8hxGBnZBIeKLTXJV pyumAievEgX2Ler6lszIljNiyZrHlqhdaQ8S3xArLPrfdmpwl/A658PJJ9ZzK93dndPh WPZN0UVVxc+U5h0Ti3EvAnfAtaiAkfebz/6EcDBAtGbPnOW/HcCCl9Wz1YtFWuep7Bv4 5i7pOXRkemQSMQP/i7jPzjParhZ4tS2HF3jZXxO6gRqdUXj1EnozeGKOK8mHSWCUo+vm U3bQ== X-Gm-Message-State: ANhLgQ3n9MynUa4ufhFlPcx43guHW495aEmqUkDYeMJikQIzykOy0y5O ibnKvpbKatEFAxTVTaPUxLtXWw== X-Google-Smtp-Source: ADFU+vtLr5xkNiaIyt5Ozz0raelxqkQC97tZxG4/MYeJahlnnqZKwK63Bzq/imqA23inH9Oocgbuag== X-Received: by 2002:aa7:850f:: with SMTP id v15mr5712127pfn.119.1585433970045; Sat, 28 Mar 2020 15:19:30 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id nk12sm6752020pjb.41.2020.03.28.15.19.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 28 Mar 2020 15:19:29 -0700 (PDT) Date: Sat, 28 Mar 2020 15:19:28 -0700 From: Kees Cook To: kernel test robot Cc: LKML , lkp@lists.01.org Subject: Re: [x86/entry] 8c5045f89b: will-it-scale.per_process_ops -12.9% regression Message-ID: <202003281505.0F481D3@keescook> References: <20200327074002.GV11705@shao2-debian> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200327074002.GV11705@shao2-debian> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 27, 2020 at 03:40:02PM +0800, kernel test robot wrote: > Greeting, > > FYI, we noticed a -12.9% regression of will-it-scale.per_process_ops due to commit: > > > commit: 8c5045f89b181a4412b698cafc9dc257192a3a65 ("x86/entry: Enable random_kstack_offset support") > https://git.kernel.org/cgit/linux/kernel/git/kees/linux.git kspp/stack/offset/agnostic/v1 > > in testcase: will-it-scale > on test machine: 288 threads Intel(R) Xeon Phi(TM) CPU 7295 @ 1.50GHz with 80G memory > with following parameters: > > nr_task: 100% > mode: process > test: lseek1 > cpufreq_governor: performance > ucode: 0x11 > > 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 Whoa. I'll take a closer look. I fail to understand how this could be happening. In this CONFIG the changes are a NOP. And that would be true for both process and thread. O_o -- Kees Cook