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 1BAF0ECAAA1 for ; Fri, 9 Sep 2022 21:22:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230407AbiIIVWT convert rfc822-to-8bit (ORCPT ); Fri, 9 Sep 2022 17:22:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56538 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230300AbiIIVWS (ORCPT ); Fri, 9 Sep 2022 17:22:18 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.86.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B8D1BEE98E for ; Fri, 9 Sep 2022 14:22:16 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-75-4x4mabv-MMeVWZPOeCQ1kQ-1; Fri, 09 Sep 2022 22:22:13 +0100 X-MC-Unique: 4x4mabv-MMeVWZPOeCQ1kQ-1 Received: from AcuMS.Aculab.com (10.202.163.4) by AcuMS.aculab.com (10.202.163.4) with Microsoft SMTP Server (TLS) id 15.0.1497.38; Fri, 9 Sep 2022 22:22:12 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.040; Fri, 9 Sep 2022 22:22:12 +0100 From: David Laight To: 'Manikandan Jagatheesan' , "peterz@infradead.org" , "bp@suse.de" , "jpoimboe@kernel.org" CC: "tglx@linutronix.de" , "mingo@redhat.com" , "bp@alien8.de" , "dave.hansen@linux.intel.com" , "x86@kernel.org" , "hpa@zytor.com" , "linux-kernel@vger.kernel.org" , "srivatsa@csail.mit.edu" , Peter Jonasson , Yiu Cho Lau , Rajender M , Abdul Anshad Azeez , "Kodeswaran Kumarasamy" , Rahul Gopakumar Subject: RE: Performance Regression in Linux Kernel 5.19 Thread-Topic: Performance Regression in Linux Kernel 5.19 Thread-Index: AQHYxD76FSnznGGLrEKJhYfY7fdHzK3Xmvxw Date: Fri, 9 Sep 2022 21:22:12 +0000 Message-ID: <3758868033fe49d5ba54e500e16df35f@AcuMS.aculab.com> References: In-Reply-To: Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: msip_labels: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Manikandan Jagatheesan > Sent: 09 September 2022 12:46 > > As part of VMware's performance regression testing for Linux > Kernel upstream releases, we have evaluated the performance > of Linux kernel 5.19 against the 5.18 release and we have > noticed performance regressions in Linux VMs on ESXi as shown > below. > - Compute(up to -70%) > - Networking(up to -30%) > - Storage(up to -13%) > > After performing the bisect between kernel 5.18 and 5.19, we > identified the root cause to be the enablement of IBRS mitigation > for spectre_v2 vulnerability by commit 6ad0ad2bf8a6 ("x86/bugs: > Report Intel retbleed vulnerability"). As a matter of interest how much faster does it go if you boot with all mitigations disabled and compile without retpolines and without page table separation? There are plenty of semi-embedded systems (even running on x86) where there are a limited set of binaries, it is difficult to add new binaries, and everything basically runs as root. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)