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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 A5B18C43387 for ; Tue, 8 Jan 2019 20:53:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 78F162070B for ; Tue, 8 Jan 2019 20:53:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729642AbfAHUxm (ORCPT ); Tue, 8 Jan 2019 15:53:42 -0500 Received: from mga14.intel.com ([192.55.52.115]:52389 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729297AbfAHUxl (ORCPT ); Tue, 8 Jan 2019 15:53:41 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 08 Jan 2019 12:53:41 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,455,1539673200"; d="scan'208";a="115214557" Received: from tassilo.jf.intel.com (HELO tassilo.localdomain) ([10.7.201.137]) by fmsmga008.fm.intel.com with ESMTP; 08 Jan 2019 12:53:41 -0800 Received: by tassilo.localdomain (Postfix, from userid 1000) id 18DC6301BEF; Tue, 8 Jan 2019 12:53:41 -0800 (PST) Date: Tue, 8 Jan 2019 12:53:41 -0800 From: Andi Kleen To: Nadav Amit Cc: Peter Zijlstra , Adrian Hunter , Ingo Molnar , Andy Lutomirski , Josh Poimboeuf , Edward Cree , "H . Peter Anvin" , Thomas Gleixner , LKML , X86 ML , Paolo Abeni , Borislav Petkov , David Woodhouse , Alexander Shishkin , songliubraving@fb.com Subject: Re: [RFC v2 0/6] x86: dynamic indirect branch promotion Message-ID: <20190108205341.GO6118@tassilo.jf.intel.com> References: <87zhshe66w.fsf@linux.intel.com> <20190107163227.GH14122@hirez.programming.kicks-ass.net> <20190108092559.GA6808@hirez.programming.kicks-ass.net> <306d38fb-7ce6-a3ec-a351-6c117559ebaa@intel.com> <20190108101058.GB6808@hirez.programming.kicks-ass.net> <20190108172721.GN6118@tassilo.jf.intel.com> <20190108190104.GC1900@hirez.programming.kicks-ass.net> <7EB5F9ED-8743-4225-BE97-8D5C8D8E0F84@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7EB5F9ED-8743-4225-BE97-8D5C8D8E0F84@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > BTW: I am not sure that static-keys are much better. Their change also > affects the control flow, and they do affect the control flow. Static keys have the same problem, but they only change infrequently so usually it's not too big a problem if you dump the kernel close to the tracing sessions. simple-pt doesn't have a similar mechanism, so it suffers more from it. -Andi