Re: dynamic ftrace - graph

[Michal Simek]

Steven Rostedt wrote:
> Hi Michal,
>
> Sorry for such a late reply, you sent this email to me at the worst
> time. My wife was having shoulder surgery and I heading for a
> conference. I fell very far behind in email and I only now just noticed
> this.

No problem. I prepared Microblaze ftrace patches. You can find them in 
linux-next. I am going to send pull request to Linus soon that's why if 
you have any your comments please let me know.

> I'll answer these ever though you may already figured it out.
>
> On Mon, 2009-11-09 at 17:52 +0100, Michal Simek wrote:
> > Hi Steve and others,
> >
> > I have working dynamic ftrace function. :-)
> >
> > I look at __ftrace_modify_code function and I have one question about.
> > Below are function which are called when I enable function_graph.
> >
> > I personally think that make more sense to call 
> > ftrace_enable_ftrace_graph_caller before ftrace_update_ftrace_func.
> > The reason for it is that graph_caller enable calling graph tracing 
> > which should be setup before ftrace_update_ftrace_func which enable 
> > whole tracing function.
>
> Have you seen any difference in output with this?

I haven't tested it. It was just suggestion. I don't know if is relevant 
or not.

Michal

> I never thought about this order too much.
>
> -- Steve
>
> > # cd ; mkdir /debug; mount -t debugfs none /debug; cat 
> > /debug/tracing/available_tracers; echo function_graph > 
> > /debug/tracing/current_tracer;echo 0 > /debug/tra
> > cing/tracing_enabled;cat /debug/tracing/trace | head -n 10
> > function_graph function sched_switch nop
> >
> > ftrace_update_ftrace_func 0xc0009100 0xc00091c4, 0xb000c000, 0x32809100
> > ftrace_enable_ftrace_graph_caller
> > # tracer: function_graph
> >
> >
> > For disabling graph trace is sequence ok I think.
> >
> > # echo function > /debug/tracing/current_tracer
> > ftrace_disable_ftrace_graph_caller
> > ftrace_update_ftrace_func 0xc006afe4 0xc00091c4, 0xb000c006, 0x3280afe4
> >
> >
> > What do you think?
> >
> > Thanks,
> > Michal


--
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/
Microblaze U-BOOT custodian
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