From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758104AbcHaCLr (ORCPT ); Tue, 30 Aug 2016 22:11:47 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:34920 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751947AbcHaCLo (ORCPT ); Tue, 30 Aug 2016 22:11:44 -0400 Date: Wed, 31 Aug 2016 11:11:38 +0900 From: Namhyung Kim To: Steven Rostedt Cc: LKML , Ingo Molnar , Josh Poimboeuf Subject: Re: [PATCH] ftrace: Access ret_stack->subtime only in the function profiler Message-ID: <20160831021138.GA26190@danjae.aot.lge.com> References: <20160829030518.5383-1-namhyung@kernel.org> <20160829160700.71dc249a@gandalf.local.home> <20160830013441.GA13062@sejong> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20160830013441.GA13062@sejong> User-Agent: Mutt/1.7.0 (2016-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 30, 2016 at 10:34:41AM +0900, Namhyung Kim wrote: > Hi Steve, > > On Mon, Aug 29, 2016 at 04:07:00PM -0400, Steven Rostedt wrote: > > On Mon, 29 Aug 2016 12:05:18 +0900 > > Namhyung Kim wrote: > > > > > The subtime is used only for function profiler with function graph > > > tracer enabled. Move the definition of subtime under > > > CONFIG_FUNCTION_PROFILER to reduce the memory usage. Also move the > > > initialization of subtime into the graph entry callback. > > > > Hmm, I think documentation needs to be updated. Although it was never > > implemented, I believe I added the subtime to not only work with the > > profiler, but also with the normal tracing (to have the time of the > > internal functions subtracted from the upper level functions). But it > > appears that part was never implemented. > > > > I'm fine with the patch, or actually implementing what graph-time > > states in Documentation/ftrace.txt. If we take this patch, that comment > > needs to be made to only mention the profiler (and the option should > > only be shown when the profiler is enabled). > > Ah, missed the documentation part. To implement it in the normal > tracing, I think we need to add 'subtime' field to struct > ftrace_graph_ret which will increase disk size. Are you ok with this? On second thought, I think I can do it by just adding value of subtime to ftrace_graph_ret.calltime when graph-time is off. Then the calltime would not be the timestamp at function entry, but it seems not guaranteed due to the sleep-time anyway. Now I wonder why it doesn't have 'duration' in the ftrace_graph_ret instead of having calltime and rettime. Thanks, Namhyung > > > > > > > > > Cc: Josh Poimboeuf > > > Signed-off-by: Namhyung Kim > > > --- > > > include/linux/ftrace.h | 2 ++ > > > kernel/trace/ftrace.c | 6 ++++++ > > > kernel/trace/trace_functions_graph.c | 1 - > > > 3 files changed, 8 insertions(+), 1 deletion(-) > > > > > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > > > index 6f93ac46e7f0..b3d34d3e0e7e 100644 > > > --- a/include/linux/ftrace.h > > > +++ b/include/linux/ftrace.h > > > @@ -794,7 +794,9 @@ struct ftrace_ret_stack { > > > unsigned long ret; > > > unsigned long func; > > > unsigned long long calltime; > > > +#ifdef CONFIG_FUNCTION_PROFILER > > > unsigned long long subtime; > > > +#endif > > > #ifdef HAVE_FUNCTION_GRAPH_FP_TEST > > > unsigned long fp; > > > #endif > > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > > > index 84752c8e28b5..2050a7652a86 100644 > > > --- a/kernel/trace/ftrace.c > > > +++ b/kernel/trace/ftrace.c > > > @@ -872,7 +872,13 @@ function_profile_call(unsigned long ip, unsigned long parent_ip, > > > #ifdef CONFIG_FUNCTION_GRAPH_TRACER > > > static int profile_graph_entry(struct ftrace_graph_ent *trace) > > > { > > > + int index = trace->depth; > > > + > > > function_profile_call(trace->func, 0, NULL, NULL); > > > + > > > + if (index >= 0 && index < FTRACE_RETFUNC_DEPTH) > > > + current->ret_stack[index].subtime = 0; > > > + > > > return 1; > > > } > > > > > > diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c > > > index 0cbe38a844fa..9c7ffa4df5a8 100644 > > > --- a/kernel/trace/trace_functions_graph.c > > > +++ b/kernel/trace/trace_functions_graph.c > > > @@ -170,7 +170,6 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth, > > > current->ret_stack[index].ret = ret; > > > current->ret_stack[index].func = func; > > > current->ret_stack[index].calltime = calltime; > > > - current->ret_stack[index].subtime = 0; > > > #ifdef HAVE_FUNCTION_GRAPH_FP_TEST > > > current->ret_stack[index].fp = frame_pointer; > > > #endif > >