Re: dynamic ftrace - graph

Michal Simek
2009-12-11T07:30:32Z

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
>>
>>