From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933303AbdC3WZ5 (ORCPT ); Thu, 30 Mar 2017 18:25:57 -0400 Received: from mail.kernel.org ([198.145.29.136]:56514 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932560AbdC3WZ4 (ORCPT ); Thu, 30 Mar 2017 18:25:56 -0400 Date: Fri, 31 Mar 2017 07:25:50 +0900 From: Masami Hiramatsu To: Steven Rostedt Cc: Namhyung Kim , Masami Hiramatsu , Ingo Molnar , LKML , kernel-team@lge.com Subject: Re: [PATCH 0/4] ftrace: Add 'function-fork' trace option (v1) Message-Id: <20170331072550.22454e289ac28c562073dcb4@kernel.org> In-Reply-To: <20170330094929.15135530@gandalf.local.home> References: <20170329014625.19346-1-namhyung@kernel.org> <20170330095442.c3d9ae668f6028cf81a7a7fd@kernel.org> <20170330094929.15135530@gandalf.local.home> X-Mailer: Sylpheed 3.5.0 (GTK+ 2.24.30; 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 List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 30 Mar 2017 09:49:29 -0400 Steven Rostedt wrote: > On Thu, 30 Mar 2017 10:40:46 +0900 > Namhyung Kim wrote: > > > Hi Masami, > > > > On Thu, Mar 30, 2017 at 9:54 AM, Masami Hiramatsu wrote: > > > On Wed, 29 Mar 2017 10:46:21 +0900 > > > Namhyung Kim wrote: > > > > > >> Hello, > > >> > > >> This patchset add 'function-fork' option to function tracer which > > >> makes pid filter to be inherited like 'event-fork' does. During the > > >> test, I found a bug of pid filter on an instance directory. The patch > > >> 1 fixes it and maybe it should go to the stable tree. > > >> > > >> The function-fork option is disabled by default as event-fork does, > > >> but we might consider changing the default since it seems to be more > > >> natural from an user's perspective IMHO. > > > > > > By the way, I thought that event-fork option also effected to > > > function tracer. Is there any reason we should separate those? > > > I mean, we can add "trace-fork" option instead of "function-fork" > > > for setting both pid filters at once. > > > > > > Thank you, > > > > I'm ok with combining two options. > > > > I prefer not. Mainly because they are two different mechanisms, and > only event-fork is available now. That sounds like implementation issue. From the viewpoint of users, they may want to use just one knob to filter both. And I didn't suggest replacing event-fork, but adding trace-fork for both, like a superset option. > trace-cmd will use ptrace if function > fork is needed. Having it separate will let trace-cmd know if it needs > to use ptrace or not for function forking. Yeah, that's a good workaround for older kernel. Thank you, -- Masami Hiramatsu