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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 AC16BC433E6 for ; Fri, 8 Jan 2021 09:52:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 637A1235FA for ; Fri, 8 Jan 2021 09:52:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728258AbhAHJwt (ORCPT ); Fri, 8 Jan 2021 04:52:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40122 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727629AbhAHJws (ORCPT ); Fri, 8 Jan 2021 04:52:48 -0500 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6CECCC0612F4 for ; Fri, 8 Jan 2021 01:52:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=1PDtrbcaBPK2Go3OlTjgm02lDmV3mwof4pPUUTeO7Z4=; b=0uEJgH+66I5JaBymO9Gh0bMRwC UITBv1j2qRhYCStpw8VpTopyJo6yv3ZOprk9DliwkJE3btxsYl0St71q7iEdB+9h4P39swUix3Hp1 ejf07vs2FQeafuQjw7kq6EOUuR0+wY4Pd4TSsxiIaSQDl6aMr36UsjCGvjedaS/P/7Yq/i/GmkzVr Ao+mxPb/i/0U1ZsWWDpBKMxsd4jsqBa7ca3bPnDoBujTNqRwSNlgx93O1BfQO2JfqJP54/3rSdJBy Cs4TH8To2KstXWc4HcHzGLTGe7/lFxsAW+ZLmuqmmcEZuadKFlmSqhIGpSDwLUPd4/1AjZBzhqeUh Ud5VKs/A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kxoR4-0000kL-6W; Fri, 08 Jan 2021 09:51:58 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 40E9D3003D8; Fri, 8 Jan 2021 10:51:56 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 2FC322BC2B3D9; Fri, 8 Jan 2021 10:51:56 +0100 (CET) Date: Fri, 8 Jan 2021 10:51:56 +0100 From: Peter Zijlstra To: David Laight Cc: 'Linus Torvalds' , Al Viro , kernel test robot , Thomas Gleixner , Ingo Molnar , Borislav Petkov , LKML , "lkp@lists.01.org" , kernel test robot , "Huang, Ying" , Feng Tang , "zhengjun.xing@intel.com" Subject: Re: [x86] d55564cfc2: will-it-scale.per_thread_ops -5.8% regression Message-ID: References: <20210107134723.GA28532@xsang-OptiPlex-9020> <20210107183358.GG3579531@ZenIV.linux.org.uk> <20210107190445.GK3579531@ZenIV.linux.org.uk> <824461ae2cb642b1b2f82fac140a98da@AcuMS.aculab.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <824461ae2cb642b1b2f82fac140a98da@AcuMS.aculab.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 08, 2021 at 09:37:45AM +0000, David Laight wrote: > The lack of spinlocks in userspace really kills you. Glibc has them, but please don't complain about lock holder preemption issues if you do actually use them ;-)