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Re: [PATCH tracing/kprobes 0/7] tracing/kprobes: kprobe-based event tracer update and perf support
- From: Frederic Weisbecker <fweisbec at gmail dot com>
- To: Masami Hiramatsu <mhiramat at redhat dot com>
- Cc: Steven Rostedt <rostedt at goodmis dot org>, Ingo Molnar <mingo at elte dot hu>, lkml <linux-kernel at vger dot kernel dot org>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Andi Kleen <ak at linux dot intel dot com>, Christoph Hellwig <hch at infradead dot org>, "Frank Ch. Eigler" <fche at redhat dot com>, "H. Peter Anvin" <hpa at zytor dot com>, Jason Baron <jbaron at redhat dot com>, Jim Keniston <jkenisto at us dot ibm dot com>, "K.Prasad" <prasad at linux dot vnet dot ibm dot com>, Lai Jiangshan <laijs at cn dot fujitsu dot com>, Li Zefan <lizf at cn dot fujitsu dot com>, Peter Zijlstra <peterz at infradead dot org>, Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>, Tom Zanussi <tzanussi at gmail dot com>, systemtap <systemtap at sources dot redhat dot com>, DLE <dle-develop at lists dot sourceforge dot net>
- Date: Mon, 14 Sep 2009 04:59:50 +0200
- Subject: Re: [PATCH tracing/kprobes 0/7] tracing/kprobes: kprobe-based event tracer update and perf support
- References: <20090910235258.22412.29317.stgit@dhcp-100-2-132.bos.redhat.com> <20090911013332.GB16396@nowhere> <4AAA74D2.9060203@redhat.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...