Re: [PATCH tracing/kprobes 0/7] tracing/kprobes: kprobe-based event tracer update and perf support

[Frederic Weisbecker <fweisbec@gmail.com>]

On Fri, Sep 11, 2009 at 12:03:30PM -0400, Masami Hiramatsu wrote:
> Frederic Weisbecker wrote:
>> May be another step in the todo-list that would be nice: define the format
>> for a type. Like it's done from ftrace events.
>
> Thanks!
>
> BTW, I'm not sure what the type means. Each event already has its own
> event ID and event_call. Could you tell me which part of ftrace I should
> refer to ?
>




Actually I meant the format for a field.
Say you define filename=arg1, it would be nice to have

	print "%s", filename

in the format file.

Hmm, now that I think about it, we can't dereference an array...for now :-)


>> I guess we should choose between the low level, very granular
>> but uninviting method "kprobe + record + trace" and also an all
>> in one quick approach.
>>
>> And that could be chosen from perf kprobe:
>>
>> Low level:
>>
>> perf kprobe --define-only [-p|-r] [probe_name] -a1 [arg1] -a2 [arg2] \
>> 	    --format="%s %...."
>>
>> perf record -e kprobes:probe_name
>> perf trace
>>
>> Quick:
>>
>> perf kprobe -p probe_name -a1 ..... cmdline| -a
>>
>> And after the profiled task is finished, it could launch perf trace
>> by itself (or wait for a Ctrl + C if -a/wide profiling)
>
> Another thought: expand record subcommand.
>
> perf record -E "p|r:probe_name,place,arg1,arg2..."
> perf trace
>
> And kprobe accept multiple definitions
>
> perf kprobe -E "p|r:probe_name,place,arg1,arg2..." -E ...


Well, perf record could also support multiple definitions
too...