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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 CA68CC64EB8 for ; Thu, 4 Oct 2018 20:08:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 83EB42083F for ; Thu, 4 Oct 2018 20:08:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 83EB42083F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zytor.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727670AbeJEDD1 (ORCPT ); Thu, 4 Oct 2018 23:03:27 -0400 Received: from terminus.zytor.com ([198.137.202.136]:45287 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727489AbeJEDD0 (ORCPT ); Thu, 4 Oct 2018 23:03:26 -0400 Received: from hanvin-mobl2.amr.corp.intel.com (jfdmzpr05-ext.jf.intel.com [134.134.139.74]) (authenticated bits=0) by mail.zytor.com (8.15.2/8.15.2) with ESMTPSA id w94K8PTg2869502 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NO); Thu, 4 Oct 2018 13:08:26 -0700 Subject: Re: [PATCH v9 04/10] x86: refcount: prevent gcc distortions To: Nadav Amit , Ingo Molnar Cc: Ingo Molnar , "linux-kernel@vger.kernel.org" , "x86@kernel.org" , Thomas Gleixner , Jan Beulich , Josh Poimboeuf , Linus Torvalds , Peter Zijlstra , Andy Lutomirski References: <20181003213100.189959-1-namit@vmware.com> <20181003213100.189959-5-namit@vmware.com> <20181004075755.GA3353@gmail.com> <20181004083333.GA9802@gmail.com> <10D29A50-C352-4407-A824-0C3C06CD8592@zytor.com> <36D6F606-6922-4057-B1F8-2B30993962AE@zytor.com> <20181004091651.GB21151@gmail.com> From: "H. Peter Anvin" Message-ID: Date: Thu, 4 Oct 2018 13:08:25 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/04/18 13:05, Nadav Amit wrote: > > Funny. Immediate-patching is what I was playing with when I encountered the > gcc issue. Performance got worse instead of improving (or at least staying > the same), because inlining got crazy. > > Anyhow, wait for my soon-to-be-sent RFC in which I define a macro called > “call” (to reduce the retpoline overhead) before you talk about damage to > the eyes. > Doing it well is *hard*, as I discovered. The actual patch is much, much, larger. -hpa