From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965359Ab1JFWUx (ORCPT ); Thu, 6 Oct 2011 18:20:53 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.125]:50711 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965348Ab1JFWUu (ORCPT ); Thu, 6 Oct 2011 18:20:50 -0400 X-Authority-Analysis: v=1.1 cv=lfM0d0QHaVz67dfwwr9cyIw6NbaGR/pZhMD6XWNi0kk= c=1 sm=0 a=msyzJTVhAHgA:10 a=5SG0PmZfjMsA:10 a=Q9fys5e9bTEA:10 a=17wjrS5wAhQaEczCPkpxpQ==:17 a=bRjG9fRkdTCjW9-B8xYA:9 a=PUjeQqilurYA:10 a=17wjrS5wAhQaEczCPkpxpQ==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.83.30 Subject: Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out From: Steven Rostedt To: Jeremy Fitzhardinge 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 Date: Thu, 06 Oct 2011 18:20:47 -0400 In-Reply-To: <4E8E275F.6010801@goop.org> 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> <4E8E275F.6010801@goop.org> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.0.3- Content-Transfer-Encoding: 7bit Message-ID: <1317939649.4729.36.camel@gandalf.stny.rr.com> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2011-10-06 at 15:10 -0700, Jeremy Fitzhardinge wrote: > On 10/06/2011 03:06 PM, Steven Rostedt wrote: > 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. Sorry, I'm still thinking jump-label for tracing over. But that said, having the nop match is the best of both worlds. I think having a update_jumplabel.c that is just like the record_mcount.c which modifies the code right after it was compiled is the best thing to do. That is, have the assembler determine what size jumps to use and update them to nops right in the object file before linking. This should be rather trivial to do. -- Steve