Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758422Ab2FALhM (ORCPT ); Fri, 1 Jun 2012 07:37:12 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:21677 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755398Ab2FALhK (ORCPT ); Fri, 1 Jun 2012 07:37:10 -0400 X-Authority-Analysis: v=2.0 cv=eIiRfQV1 c=1 sm=0 a=ZycB6UtQUfgMyuk2+PxD7w==:17 a=XQbtiDEiEegA:10 a=A73EdQgzBtYA:10 a=5SG0PmZfjMsA:10 a=Q9fys5e9bTEA:10 a=meVymXHHAAAA:8 a=ayC55rCoAAAA:8 a=7LbZ8pxXUWzXXegPjNQA:9 a=PUjeQqilurYA:10 a=ZycB6UtQUfgMyuk2+PxD7w==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.80.29 Message-ID: <1338550627.13348.462.camel@gandalf.stny.rr.com> Subject: Re: Re: [PATCH 1/5] ftrace: Synchronize variable setting with breakpoints From: Steven Rostedt To: Masami Hiramatsu Cc: Peter Zijlstra , Mathieu Desnoyers , linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Frederic Weisbecker , "H. Peter Anvin" , Dave Jones , Andi Kleen , acme , yrl.pp-manager.tt@hitachi.com Date: Fri, 01 Jun 2012 07:37:07 -0400 In-Reply-To: <4FC84AC8.3020601@hitachi.com> References: <20120531012829.160060586@goodmis.org> <20120531020440.476352979@goodmis.org> <1338462398.28384.52.camel@twins> <1338473302.13348.336.camel@gandalf.stny.rr.com> <1338486029.28384.93.camel@twins> <1338486820.13348.366.camel@gandalf.stny.rr.com> <1338487413.28384.103.camel@twins> <1338490218.13348.379.camel@gandalf.stny.rr.com> <1338491176.28384.114.camel@twins> <20120531195529.GA22976@Krystal> <1338495006.13348.418.camel@gandalf.stny.rr.com> <1338495969.28384.119.camel@twins> <1338496676.13348.430.camel@gandalf.stny.rr.com> <1338496857.28384.124.camel@twins> <1338497360.13348.438.camel@gandalf.stny.rr.com> <4FC84AC8.3020601@hitachi.com> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.2.2-1 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1474 Lines: 33 On Fri, 2012-06-01 at 13:53 +0900, Masami Hiramatsu wrote: > Hmm, why don't we have two text_poke interfaces for single and > batch? As like dyn_ftrace, since modifying massive points takes > a lot time, so we may have additional kconfig something like > CONFIG_QUICK_BATCH_TEXT_POKE which switches text area to rw while > batch text_poke. > I'll be working on patches to consolidate the two after I get everything else working :-) I still need to work on the ftrace kprobe stuff too. I hate having a config option to switch between the two, except for something that can be there if we find the new approach is buggy (like we have with lockdep). That may be a solution for this if we don't agree on one now. That is, bring back stop_machine() when LOCKDEP is enabled. But that should only be a temporary work around not a true fix. I have no problem with having most of the modifying code be shared between text_poke and ftrace. I guess the question is, do we want to do it only with the FIXMAP or do we want text_poke and ftrace to use the rw method for large batches. Heck, we can set a limit. If we are going to update more that 100 locations, we switch the kernel to rw, otherwise we do the FIXMAP update. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/