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 9CC7EECAAA1 for ; Fri, 9 Sep 2022 13:19:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229914AbiIINTU (ORCPT ); Fri, 9 Sep 2022 09:19:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43516 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229771AbiIINTS (ORCPT ); Fri, 9 Sep 2022 09:19:18 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A1754AB1B4 for ; Fri, 9 Sep 2022 06:19:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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=uu4FKZ6m8FqFuZxmlF95kxb0xNsagokSRxqsYzwUQsI=; b=ut5fVKXMdS+luwtzvFplggRB2M O4LjNb16pGtC/zWiwMotqWJWFimyX9raS8SgcXGAExwIHDhEwnhgVDODCFwI/+2z4ms0vMPyuaMqy nSk5n6JBabnvBGEYxdwDu/MWRO84OjlfgIL6R7pIhsPZrf0zNiILBbiHQDaQ/qsk7HwJ0taNPDhuH dPCKFvRf9OV+3wdzi0MnzxVuYq6RqzeArE8pKvZ4Ajuq177bywBsUXfhMzxrorQCEyFSwe7IXNfln n3u/IArizmeE7KodnB3Q2jwSWTHBRyTku2ae/1HRHQckbr5vTK87I8byBR0v0PZSRBU6ERsEpiNil fLvDa1QA==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1oWdu8-00DHcd-QL; Fri, 09 Sep 2022 13:18:44 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id D84D6300023; Fri, 9 Sep 2022 15:18:40 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id AEA33201AF2DB; Fri, 9 Sep 2022 15:18:40 +0200 (CEST) Date: Fri, 9 Sep 2022 15:18:40 +0200 From: Peter Zijlstra To: Manikandan Jagatheesan Cc: "bp@suse.de" , "jpoimboe@kernel.org" , "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 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 09, 2022 at 11:46:08AM +0000, Manikandan Jagatheesan wrote: > 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"). > > To confirm this, we have disabled the above security mitigation > through kernel boot parameter(spectre_v2=off) in 5.19 and re-ran > our tests & confirmed that the performance was on-par with > 5.18 release. Well, duh.. :-)