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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 6F9D5FA372A for ; Wed, 16 Oct 2019 10:15:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5244120650 for ; Wed, 16 Oct 2019 10:15:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404617AbfJPKPy (ORCPT ); Wed, 16 Oct 2019 06:15:54 -0400 Received: from mx2.suse.de ([195.135.220.15]:50398 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2404606AbfJPKPx (ORCPT ); Wed, 16 Oct 2019 06:15:53 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id E0F3DB266; Wed, 16 Oct 2019 10:15:51 +0000 (UTC) Date: Wed, 16 Oct 2019 12:15:50 +0200 (CEST) From: Miroslav Benes To: Peter Zijlstra cc: Steven Rostedt , Joe Lawrence , Jessica Yu , x86@kernel.org, linux-kernel@vger.kernel.org, mhiramat@kernel.org, bristot@redhat.com, jbaron@akamai.com, torvalds@linux-foundation.org, tglx@linutronix.de, mingo@kernel.org, namit@vmware.com, hpa@zytor.com, luto@kernel.org, ard.biesheuvel@linaro.org, jpoimboe@redhat.com, live-patching@vger.kernel.org Subject: Re: [PATCH v3 5/6] x86/ftrace: Use text_poke() In-Reply-To: <20191016074217.GL2328@hirez.programming.kicks-ass.net> Message-ID: References: <20191010115449.22044b53@gandalf.local.home> <20191010172819.GS2328@hirez.programming.kicks-ass.net> <20191011125903.GN2359@hirez.programming.kicks-ass.net> <20191015130739.GA23565@linux-8ccs> <20191015135634.GK2328@hirez.programming.kicks-ass.net> <88bab814-ea24-ece9-2bc0-7a1e10a62f12@redhat.com> <20191015153120.GA21580@linux-8ccs> <7e9c7dd1-809e-f130-26a3-3d3328477437@redhat.com> <20191015182705.1aeec284@gandalf.local.home> <20191016074217.GL2328@hirez.programming.kicks-ass.net> User-Agent: Alpine 2.21 (LSU 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 16 Oct 2019, Peter Zijlstra wrote: > > which are not compatible with livepatching. GCC upstream now has > > -flive-patching option, which disables all those interfering optimizations. > > Which, IIRC, has a significant performance impact and should thus really > not be used... Fortunately, the impact is negligible. Miroslav