Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751541AbdCCA6N (ORCPT ); Thu, 2 Mar 2017 19:58:13 -0500 Received: from mga14.intel.com ([192.55.52.115]:2789 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750941AbdCCA6M (ORCPT ); Thu, 2 Mar 2017 19:58:12 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.35,234,1484035200"; d="scan'208";a="830349458" Message-ID: <1488502497.7212.24.camel@linux.intel.com> Subject: Re: [PATCH] ftrace: add ftrace_graph_max_depth kernel parameter From: Todd Brandt Reply-To: todd.e.brandt@linux.intel.com To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, todd.e.brandt@intel.com Date: Thu, 02 Mar 2017 16:54:57 -0800 In-Reply-To: <20170302193943.3117fca7@gandalf.local.home> References: <1488499935-23216-1-git-send-email-todd.e.brandt@linux.intel.com> <20170302193827.6f5ee2eb@gandalf.local.home> <20170302193943.3117fca7@gandalf.local.home> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.11-0ubuntu3 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1941 Lines: 47 On Thu, 2017-03-02 at 19:39 -0500, Steven Rostedt wrote: > On Thu, 2 Mar 2017 19:38:27 -0500 > Steven Rostedt wrote: > > > On Thu, 2 Mar 2017 16:12:15 -0800 > > Todd Brandt wrote: > > > > > Early trace callgraphs can be extremely large on systems with > > > several seconds of boot time. The max_depth parameter limits how > > > deep the graph trace goes and reduces the output size. This > > > parameter is the same as the max_graph_depth file in debugfs. > > > > I'll take this with one modification I'll make. s/debugfs/tracefs/ > > because it's really the tracefs file system now. It just happens to be > > automatically mounted in the debugfs file system. But can be by itself > > in /sys/kernel/tracing/ thanks! BTW I had one other question for you, is it possible to move the ftrace module's initialization further up the queue? ATM it initializes at about 600ms into boot, which is fine since most of the performance issues are happening at 1000ms+. But eventually it might be nice to trace some of the earlier init code. > > > > -- Steve > > > > > > > > Signed-off-by: Todd Brandt > > > --- > > > Documentation/admin-guide/kernel-parameters.txt | 6 ++++++ > > > kernel/trace/ftrace.c | 9 +++++++++ > > > 2 files changed, 15 insertions(+) > > > > > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > > > index 986e443..1a8575f 100644 > > > --- a/Documentation/admin-guide/kernel-parameters.txt > > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > > @@ -1183,6 +1183,12 @@ > > > functions that can be changed at run time by the > > > set_graph_notrace file in the debugfs tracing directory. > > I need to make a patch to update the old documentation to reflect this > as well. But I'll do that another time. > > -- Steve