From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753359Ab2CXOzg (ORCPT ); Sat, 24 Mar 2012 10:55:36 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:19279 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751234Ab2CXOzf (ORCPT ); Sat, 24 Mar 2012 10:55:35 -0400 X-Authority-Analysis: v=2.0 cv=LrMQOwhc c=1 sm=0 a=ZycB6UtQUfgMyuk2+PxD7w==:17 a=XQbtiDEiEegA:10 a=wBLf1-ka6lYA:10 a=5SG0PmZfjMsA:10 a=IkcTkHD0fZMA:10 a=MIs9pYtiac-Rw8KjcOIA:9 a=QEXdDO2ut3YA:10 a=ZycB6UtQUfgMyuk2+PxD7w==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.80.29 Subject: Re: [PATCH 1/1] ftrace: fix dynamic ftrace filter reset issue From: Steven Rostedt To: Rajesh Bhagat Cc: Frederic Weisbecker , Ingo Molnar , linux-kernel@vger.kernel.org In-Reply-To: References: <1332531400.23924.71.camel@gandalf.stny.rr.com> Content-Type: text/plain; charset="UTF-8" Date: Sat, 24 Mar 2012 09:55:05 -0400 Message-ID: <1332597305.12799.2.camel@acer.local.home> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2012-03-24 at 09:47 +0530, Rajesh Bhagat wrote: > Hi Steven, > > Thanks for the reply. > > I was wondering, why would a user reset the trace __explicitly__ > without even using it. > That is why i created a patch for it. > > >> /debug/tracing # echo function > current_tracer ^ | user starts using tracer > >> /debug/tracing # cat trace <------ Not performed > >> /debug/tracing # echo schedule > set_ftrace_filter > >> /debug/tracing # echo function > current_trace > >> /debug/tracing # cat trace <------- Only this is performed Why the first "echo function"? That means you just started using the tracer. You can (and should) do: # echo schedule > set_ftrace_filter # echo function > current_tracer This IIRC is the documented way of using it. That said, I may consider taking the patch, as another way of resetting the tracer. I have to see what workflows it will affect first. -- Steve