From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752296AbeERPqq (ORCPT ); Fri, 18 May 2018 11:46:46 -0400 Received: from mail-cys01nam02on0065.outbound.protection.outlook.com ([104.47.37.65]:10462 "EHLO NAM02-CY1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751450AbeERPqf (ORCPT ); Fri, 18 May 2018 11:46:35 -0400 From: Nadav Amit To: Borislav Petkov CC: Ingo Molnar , Peter Zijlstra , "linux-kernel@vger.kernel.org" , "x86@kernel.org" , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Josh Poimboeuf , Linus Torvalds , Andy Lutomirski , Peter Zijlstra , Denys Vlasenko Subject: Re: [PATCH 2/6] x86: bug: prevent gcc distortions Thread-Topic: [PATCH 2/6] x86: bug: prevent gcc distortions Thread-Index: AQHT7jbL50o+w3m6PkeKHm2HX6GyP6Q1H7KAgAAEMwCAACDIAIAAShCAgAASAACAAAGeAA== Date: Fri, 18 May 2018 15:46:33 +0000 Message-ID: <30EDFE9B-CA25-42EE-A57F-E3054B84223E@vmware.com> References: <20180517161402.78089-1-namit@vmware.com> <20180517161402.78089-3-namit@vmware.com> <20180518075853.GD12217@hirez.programming.kicks-ass.net> <20180518081354.GA11379@gmail.com> <20180518101114.GB17285@pd.tnic> <20180518154044.GE17285@pd.tnic> In-Reply-To: <20180518154044.GE17285@pd.tnic> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [208.91.2.2] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;SN2PR05MB2656;7:1bawnbben9w7G3nGhQ0ir0dDRvWPj2laL9S+8LuUEo8PPfrM9mrgI4HS+IGHbb6FcogY6Z4Xm20VwitEGdRfqKYvTS5HYwf8ndOezfHwGh3+mIJGCilq7QVajrzPxvrLA2BIhmv/jaDqm3G7yWfQTWFoL/Jnzpb4CLFijm6cwgFSzWfCtZej+H4LHbfpHojER99ui4GGy4wx/V+xq65gRjeKXyq7zkzKi8hsDOFhywwu2IRqy2mXLEIgkZ2k3/bx;20:rEmbcO0USK5Fd2Fd8IvfejyYZ4MYK18LBwMB24DhZX0aMapt8GExkX4K6e0jZu3ECSBZsGQmhVAhSfvODzI8pE8Uws7dV5k3gtfnvFLbxOoTuOCYMhIBtsAD9UnwgPiVjTWlO8w7jE2OUfwULd6eu3Tt7PBlwaCu6Ak8MkD3XdE= x-ms-exchange-antispam-srfa-diagnostics: SOS; x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(5600026)(4534165)(4627221)(201703031133081)(201702281549075)(2017052603328)(7153060)(7193020);SRVR:SN2PR05MB2656; x-ms-traffictypediagnostic: SN2PR05MB2656: authentication-results: spf=none (sender IP is ) smtp.mailfrom=namit@vmware.com; x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:; x-ms-exchange-senderadcheck: 1 x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(8211001083)(6040522)(2401047)(5005006)(8121501046)(3002001)(3231254)(944501410)(52105095)(93006095)(93001095)(10201501046)(149027)(150027)(6041310)(20161123564045)(20161123558120)(20161123560045)(20161123562045)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(6072148)(201708071742011)(7699016);SRVR:SN2PR05MB2656;BCL:0;PCL:0;RULEID:;SRVR:SN2PR05MB2656; x-forefront-prvs: 0676F530A9 x-forefront-antispam-report: SFV:NSPM;SFS:(10009020)(396003)(376002)(39860400002)(39380400002)(346002)(366004)(199004)(189003)(476003)(97736004)(486006)(2616005)(83716003)(446003)(11346002)(7736002)(316002)(6916009)(53936002)(66066001)(6512007)(68736007)(2900100001)(54906003)(305945005)(36756003)(86362001)(6506007)(82746002)(8936002)(5660300001)(99286004)(76176011)(81156014)(81166006)(8676002)(7416002)(4326008)(102836004)(3280700002)(6116002)(2906002)(6246003)(6486002)(14454004)(229853002)(5250100002)(3660700001)(33656002)(478600001)(105586002)(93886005)(106356001)(186003)(3846002)(26005)(25786009)(6436002);DIR:OUT;SFP:1101;SCL:1;SRVR:SN2PR05MB2656;H:SN2PR05MB2654.namprd05.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1;MX:1; x-microsoft-antispam-message-info: qLkVf5Z73h98lYhQzZDTfTvJZZ4LF+Ke72pnODAELlxC54Kbx8X1/MvQLXswlmd0eyd2btJZER1bgbuH/+tKEh1qrQCeR28cZPHvU6/i0rSBnfPuXx98LvelSlbJLfJxblKeImbz+y90Y0HCEZd2/j7oTYooVTwHB5Z4I6C/KYTnurv8PFeIhpriiLPQz64W spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="utf-8" Content-ID: <0339D9222D6AEB4C95F86E5C81D4D5ED@namprd05.prod.outlook.com> MIME-Version: 1.0 X-MS-Office365-Filtering-Correlation-Id: 69452fe9-1002-4b51-5beb-08d5bcd68803 X-OriginatorOrg: vmware.com X-MS-Exchange-CrossTenant-Network-Message-Id: 69452fe9-1002-4b51-5beb-08d5bcd68803 X-MS-Exchange-CrossTenant-originalarrivaltime: 18 May 2018 15:46:33.2175 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: b39138ca-3cee-4b4a-a4d6-cd83d9dd62f0 X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN2PR05MB2656 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id w4IFkrOR029749 Borislav Petkov wrote: > On Fri, May 18, 2018 at 02:36:21PM +0000, Nadav Amit wrote: >> I didn’t try too hard to find more affected (micro)benchmarks, but I am >> pretty sure there are: > > So you being pretty sure there are, doesn't make me go, oh, ok, then, > this is an uglification we should try to live with. It is still ugly > with no proven benefit from it. In case you didn’t read the cover-letter: the patch-set does give a 2% performance improvement for #PF-MADV_DONTNEED microbenchmark loop.