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=-1.0 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 B2C5AC43441 for ; Fri, 9 Nov 2018 19:37:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6136A20892 for ; Fri, 9 Nov 2018 19:37:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6136A20892 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org 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 S1727470AbeKJFTG (ORCPT ); Sat, 10 Nov 2018 00:19:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:47346 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725758AbeKJFTG (ORCPT ); Sat, 10 Nov 2018 00:19:06 -0500 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9EA3C20855; Fri, 9 Nov 2018 19:37:04 +0000 (UTC) Date: Fri, 9 Nov 2018 14:37:03 -0500 From: Steven Rostedt To: Andy Lutomirski Cc: Josh Poimboeuf , Andy Lutomirski , Ingo Molnar , LKML , X86 ML , Ard Biesheuvel , Peter Zijlstra , Thomas Gleixner , Linus Torvalds , Masami Hiramatsu , Jason Baron , Jiri Kosina , David Laight , Borislav Petkov Subject: Re: [PATCH RFC 0/3] Static calls Message-ID: <20181109143703.5f2205bf@gandalf.local.home> In-Reply-To: <979DB163-EFBD-41BB-8481-155AAF526E72@amacapital.net> References: <20181109072811.GB86700@gmail.com> <20181109152139.zig45f6gp24btfbc@treble> <20181109164137.5cngbfrkm4ihj4ra@treble> <20181109134241.5f4ce3be@gandalf.local.home> <979DB163-EFBD-41BB-8481-155AAF526E72@amacapital.net> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 9 Nov 2018 11:05:51 -0800 Andy Lutomirski wrote: > > Not sure what Andy was talking about, but I'm currently implementing > > tracepoints to use this, as tracepoints use indirect calls, and are a > > prime candidate for static calls, as I showed in my original RFC of > > this feature. > > > > > > Indeed. > > Although I had assumed that tracepoints already had appropriate jump label magic. It does. But that's not the problem I was trying to solve. It's that tracing took a 8% noise dive with retpolines when enabled (hackbench slowed down by 8% with all the trace events enabled compared to all trace events enabled without retpoline). That is, normal users (those not tracinng) are not affected by trace events slowing down by retpoline. Those that care about performance when they are tracing, are affected by retpoline, quite drastically. I'm doing another test run and measurements, to see how the unoptimized trampolines help, followed by the trampoline case. -- Steve