Re: [PATCH v7 2/2] Tracepoint: register/unregister struct tracepoint

[Mathieu Desnoyers]

----- Original Message -----
> From: "Steven Rostedt" <rostedt@xxxxxxxxxxx>
> To: "Mathieu Desnoyers" <mathieu.desnoyers@xxxxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx, "Ingo Molnar" <mingo@xxxxxxxxxx>, "Frederic Weisbecker" <fweisbec@xxxxxxxxx>,
> "Andrew Morton" <akpm@xxxxxxxxxxxxxxxxxxxx>, "Frank Ch. Eigler" <fche@xxxxxxxxxx>, "Johannes Berg"
> <johannes.berg@xxxxxxxxx>
> Sent: Friday, March 21, 2014 3:40:00 PM
> Subject: Re: [PATCH v7 2/2] Tracepoint: register/unregister struct tracepoint
> 
> On Fri, 21 Mar 2014 01:19:02 -0400
> 
> > diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
> > index 4e4cc28..1592c1c 100644
> > --- a/include/linux/ftrace_event.h
> > +++ b/include/linux/ftrace_event.h
> > @@ -230,6 +230,7 @@ struct ftrace_event_call {
> >  	struct list_head	list;
> >  	struct ftrace_event_class *class;
> >  	char			*name;
> > +	struct tracepoint	*tp;
> 
> 
> This change right here just added 17K to the kernel (on a minimum config):
> 
>    text	   data	    bss	    dec	    hex	filename
> 8425515	2018936	1302528	11746979	 b33ea3	vmlinux.orig
> 8424914	2036472	1302528	11763914	 b380ca	vmlinux
> 
> The two are redundant. Might as well remove .name and then
> use .tp->name for referencing the name of the event.

What should we do about:

kernel/trace/trace_export.c:

struct ftrace_event_call __used event_##call = {                        \
        .name                   = #call,                                \
        .event.type             = etype,                                \
        .class                  = &event_class_ftrace_##call,           \
        .print_fmt              = print,                                \
        .flags                  = TRACE_EVENT_FL_IGNORE_ENABLE | TRACE_EVENT_FL_USE_CALL_FILTER, \
}; 

when replacing the .name for a .tp->name, it is unclear what the
tracepoint structure should be (is there even one ?).

Thanks,

Mathieu


> 
> -- Steve
> 
> 
> >  	struct trace_event	event;
> >  	const char		*print_fmt;
> >  	struct event_filter	*filter;
> 

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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