Re: DTrace-like analysis possible with future Linux kernels?

Tomasz Kłoczko
2004-08-23T17:38:02Z

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On Sun, 22 Aug 2004, Alan Cox wrote:

> On Sul, 2004-08-22 at 19:27, Tomasz K?oczko wrote:
>> Using yor thing path: KProbe/Dtrace is for development and yes it must
>> depend on DEBUG_KERNEL.
>> ptrace() is also for tracing and ver offen used by developers but it is
>> enabled by default and it is not only for developers. So .. ptrace() must
>> also depend on DEBUG_KERNEL.
>
> ptrace is for debugging user space, as for example is oprofile. kprobes
> is for debugging including kernel internal goings on

Yes. It *is* for debuging/tracing in kernel space but like DTrace is
*also* in user space.

>> compilation stage). In Solaris kernel exist few thousands avalaible probes
>> and IIRC only very small subset is "near zero effect" (uses nop
>> instructions).
>
> Sounds like a kprobes clone 8).

Look on some time stamps both projects.
Seems KProbes is clone DTrace ..

>>> OProfile doesn't require this.
>>
>> As same as KProbe/DTrace. Can you use OProfile for something other tnan
>> profiling ? Probably yes and this answer opens: probably it will be good
>> prepare some common code for KProbe and Oprofile.
>
> Oprofile lets you work on stuff like cache affinity, tuning array walks
> and prefetches. Short of running the app under cachegrind its one of the
> most detailed ways of getting all the profile register data from the x86
> processors.

The same is KProbes but you can combined with small programs associated
with called probes. Again: DTrace/KProbes is much more than traditional
profiling/tracing/measuring tools.

>> So it will be good stop disscuss about "yes or no ?" and start about
>> "how and when in Linux ?" ..
>
> When you send patches ?

KProbes patches was annouced on lkml few times.

kloczek
--
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*Ludzie nie mają problemów, tylko sobie sami je stwarzają*
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Tomasz Kłoczko, sys adm @zie.pg.gda.pl|*e-mail: kloczek@rudy.mif.pg.gda.pl*