Re: [PATCH, RFC] sputrace: use the generic event tracer

[Ingo Molnar <mingo@elte.hu>]

* Christoph Hellwig <hch@lst.de> wrote:

> On Wed, May 06, 2009 at 12:57:48PM +0200, Ingo Molnar wrote:
> > Nice! Needs also an Ack from PowerPC folks before we can do this. 
> > The cross section to other powerpc code seems to be rather low.
> 
> cbe-oss-dev is the Cell list.

( ... and linuxppc-dev. And since it's all a sub-architecture of 
  PowerPC and Cell changes go upstream via the PowerPC tree, it's 
  nice to have the attention (and acks) of generic-arch maintainers 
  as well (if they are interested). And even if it's OK, Ben and 
  Arnd obviously calls the shots when it comes to workflow details: 
  in which tree and how to queue it up. )

> > > -config SPU_TRACE
> > > -	tristate "SPU event tracing support"
> > > -	depends on SPU_FS && MARKERS
> > > -	help
> > > -	  This option allows reading a trace of spu-related events through
> > > -	  the sputrace file in procfs.
> > 
> > I think we should keep this option around.
> 
> Why?  trace_events that aren't enabled are extremly low overhead.
> And most in the current tree are non-optional.

It is general curtesy to maintain the old Kconfig structure and ease 
migration to a new facility.

Part of the "being nice" excercise ;-)

> > > +# magic for the trace events
> > > +CFLAGS_sched.o := -I$(src)
> > 
> > Steve, i'm wondering whether this type of Makefile hackery (caused 
> > by modular tracepoints) could be eliminated ...
> 
> We would just have to include the header file with "" instead of 
> <>. But I remember Steve not liking this when we talked about it.

Yeah. But changing Makefiles isnt particularly clean either ...

And adding -I$(src) can have side-effects: we often have a local 
foo.h while an include/linux/foo.h as well.

	Ingo