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Re: Notes from the systemtap BOF


On Fri, Jul 29, 2005 at 01:18:51AM -0400, Karim Yaghmour wrote:
> Hmm... I guess I kind of understand what you're trying to achieve: make it
> simple for people to add ad-hoc trace points that don't require user-space
> tool modifications to make them meaningfull. I can see the usefullness of
> this, but ... more below.

    I think we're getting closer to the issue but I likely got lost along a
tangent.  Please forgive the missuse of tapset terminology.
    Let's say that we have a tapset of core trace events such as a
reschedule or handling an interrupt.  My understanding is that a mapping
layer is proposed in user space to map tap physical location to actual
meaning.  Everyone is happy.
    Now I come along and want to do some additional ad hoc exploration.  I
add a few tap points to the reschedule function and the core tap is no
longer the first tap in the function.  I'm concerned that this is a 2-part
exercise: add the ad hoc tap and change the user space mapping.  If I do
this several times and then want to store and compare the results later, you
can see why I'm concerned.

    Can we come up with a way to add ad hoc points that don't need to be in
the mapping without having to update the mapping to point at the new
physical locations?
	 	   				Thanks,
						       Michael
-- 
Michael A. Raymond              Office: (651) 683-3434
Core OS Group                   Real-Time System Software


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