Re: [patch 10/10] Scheduler profiling - Use immediate values

Mathieu Desnoyers
2007-07-06T23:43:25Z

* Adrian Bunk (bunk@stusta.de) wrote:
> On Fri, Jul 06, 2007 at 06:14:10PM -0400, Chuck Ebbert wrote:
> > On 07/06/2007 07:44 AM, Andi Kleen wrote:
> > > I think the optimization is a good idea, although i dislike it
> > > that it is complicated for the dynamic markers. If it was just
> > > static it would be much simpler.
> >
> > Another thing to consider is that there might be hundreds of these
> > probes/tracepoints active in an instrumented kernel. The overhead
> > adds up fast, so the gain may be worth all the pain.
>
> Only if you want to squeeze the last bit of performance out of
> _debugging_ functionality.
>
> You avoid all the pain if you simply don't use debugging functionality
> on production systems.
>

Adrian,

Please have a look at my markers posts, especially:

http://www.ussg.iu.edu/hypermail/linux/kernel/0707.0/0669.html

And also look into OLS 2007 proceedings for Martin Bligh's paper on
Debugging Google sized clusters. It basically makes the case for adding
functionnality to debug _user space_ problems on production systems that
can be turned on dynamically.

Mathieu

> cu
> Adrian
>
> --
>
> "Is there not promise of rain?" Ling Tan asked suddenly out
> of the darkness. There had been need of rain for many days.
> "Only a promise," Lao Er said.
> Pearl S. Buck - Dragon Seed
>

--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
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