Messages in this thread | | | Date | Wed, 04 Nov 2009 09:11:33 -0500 | From | Masami Hiramatsu <> | Subject | Re: [PATCH -tip perf/probes 0/5] perf-probe and kprobe-tracer updates |
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Frederic Weisbecker wrote: > On Tue, Nov 03, 2009 at 07:12:04PM -0500, Masami Hiramatsu wrote: >> BTW, I think perf-probe and kprobe-event might better share >> similar syntax for not confusing users. And for that purpose, >> perf-probe syntax should introduce event/group specifier, >> for example, > > > I personally more imagine the debugfs kprobe-event interface as > something used by higher level applications rather than users. > > I've tried to use kprobe events directly by the past to do > some debugging, and once I wanted to go further a simple function > probe, like fetching a variable or putting a probe in a given branch, > it rapidly grew into a pain: I had to read assembly code, guess > which register was matching which variable, etc... It works, but > it takes too much time, and printk() rapidly becomes a temptation :) > > It too low-level, but its use through perf brings all that to the > human dimension. > > So, I'm not sure we really need to have such tight syntax between > both, since the debugfs more likely behaves as a gateway, something > I don't imagine to be used broadly as an end-user interface but mostly > as a kernel interface.
I see, and I also found that the syntax never be same, since perf-probe doesn't need argument names etc. kprobe_events interface may be mostly for higher level scripts or programs.
> Especially we shouldn't break the perf probe syntax simplicity > just because we want both syntaxes to be tight.
Agreed. OK, so let it be :-)
> (Nothing related to the event/group feature itself, it's just an > opinion about the need of this similarity between two interfaces). > > >> perf probe "newgroup:newevnt=func:10 arg1 arg2" >> >> adds the newevent under newgroup. On the other hand, ftrace >> users can also add a new event as below; >> >> echo 'newgroup:newevent=func+0x18 arg1=$a1 arg2=$a2'> kprobe_events >> >> Any thoughts? > > > Yeah, that would probably be nice, especially once we have a good > collection of probes to handle and to organize in a sensical output. > > But it would be better to have that as an optional thing: > > perf probe "[group:name=]func...."
Sure, of course it should be optional. :-)
> so that we keep the simplicity of: > > perf probe func > > I guess you meant it as optional already, but just in case... :)
Thank you :-)
-- Masami Hiramatsu
Software Engineer Hitachi Computer Products (America), Inc. Software Solutions Division
e-mail: mhiramat@redhat.com
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