Messages in this thread | | | Date | Tue, 30 Aug 2016 10:34:41 +0900 | From | Namhyung Kim <> | Subject | Re: [PATCH] ftrace: Access ret_stack->subtime only in the function profiler |
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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 <namhyung@kernel.org> 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?
Thanks, Namhyung
> > > > > Cc: Josh Poimboeuf <jpoimboe@redhat.com> > > Signed-off-by: Namhyung Kim <namhyung@kernel.org> > > --- > > 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 >
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