From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935908Ab1JFWKp (ORCPT ); Thu, 6 Oct 2011 18:10:45 -0400 Received: from claw.goop.org ([74.207.240.146]:34606 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935612Ab1JFWKn (ORCPT ); Thu, 6 Oct 2011 18:10:43 -0400 Message-ID: <4E8E275F.6010801@goop.org> Date: Thu, 06 Oct 2011 15:10:39 -0700 From: Jeremy Fitzhardinge User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:7.0.1) Gecko/20110930 Thunderbird/7.0.1 MIME-Version: 1.0 To: Steven Rostedt CC: Richard Henderson , Jason Baron , "H. Peter Anvin" , "David S. Miller" , David Daney , Michael Ellerman , Jan Glauber , the arch/x86 maintainers , Xen Devel , Linux Kernel Mailing List , Jeremy Fitzhardinge , peterz@infradead.org Subject: Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out References: <477dead9647029012f93c651f2892ed0e86b89e7.1317506051.git.jeremy.fitzhardinge@citrix.com> <20111003150205.GB2462@redhat.com> <4E89E28C.7010700@goop.org> <20111004141011.GA2520@redhat.com> <4E8B3489.60902@zytor.com> <4E8CF348.4080405@goop.org> <4E8CF385.2080804@zytor.com> <4E8DEB19.1050509@goop.org> <20111006181055.GA2505@redhat.com> <1317925615.4729.14.camel@gandalf.stny.rr.com> <4E8DF870.6010000@redhat.com> <1317929321.4729.17.camel@gandalf.stny.rr.com> <4E8E20CD.5030207@goop.org> <1317938775.4729.29.camel@gandalf.stny.rr.com> In-Reply-To: <1317938775.4729.29.camel@gandalf.stny.rr.com> X-Enigmail-Version: 1.3.2 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/06/2011 03:06 PM, Steven Rostedt wrote: > But it only speeds up the tracing case. The non-tracing case is a nop > and 5bytes is 5bytes regardless. > > Did you see a 5% speed up while tracing was happening? How did you do > your test. I find a 5 byte compared to a 2 byte jump being negligible > with the rest of the overhead of tracing, but I could be wrong. You're right, this was a completely artificial microbenchmark. In practice the improvement would be a much smaller effect. But bear in mind, I'm not using jump-label for tracing. While its important for the "disabled" state to be quick, performance of the "enabled" state is also important. Thanks, J