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Re: Notes from the systemtap BOF


On Wed, Jul 27, 2005 at 10:18:35PM -0400, Karim Yaghmour wrote:
> > I agree on the basic idea of Michael of the (name, id) per event tuple, but I
> > add this thought : the id can be derived from the name dynamically. It leaves us
> > with the name as an identifier for an event (which might include the location
> > (module name, base name) where this name is declared, which is semantically
> > clear.
> 
> Sorry, this is still an overhead on maintainers. It still requires them
> to check whether two separate events have the same name yet different
> declarations. Adding to the maintainers' workload is guaranteeing that
> we'll show up as "enemy" on the radars of many. Let's not go there.

    If I were to rewrite the scheduler I would need to move the trace points
to the appropriate place.  I think it is therefor more correct to say that
we desire an interface with the minimum possible maintenance required.

    You've pointed out that we don't want developers to have to look for
name collision, and we want to be able to refer to trace points by some
number.  File / function location gets us close to this but has the downside
that meaning should be separate from location.
    We need to support core events and ad hoc exploration.  If I were adding
a new piece of code that I'd like traced, I'd like to have the option to
have it show up as some standard event or just be some temporary trace that
I'll remove later.
    Perhaps we can find a compromise.  Many tools and we ourselves currently
have a central .h file that defines standard events.  If it's simple and
well layed out then people will use it and won't need to modify it.  For
other trace points I think that position based IDs are fine.
      	    	     	   		       	   Thanks,
						   	  Michael
-- 
Michael A. Raymond              Office: (651) 683-3434
Core OS Group                   Real-Time System Software


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