Next: Overheads in And-Parallelism
Up: Overheads in Or-Parallelism
Previous: Stack Copying:
many of the considerations made for stack-copying are valid
also in the case of Binding Arrays. The execution model is quite similar, in the fact that
the scheduler will be called upon backtracking in the public part of the tree (part that is
shared between different agents), and it will eventually send a request to an agent for
taking work from a new choice point. In the Binding Arrays case the operation of taking
work is considerably faster, since the only activity required is updating the
content of the binding arrays. On the other hand, the model has an additional overhead due
to the fact that every conditional variable is now stored in binding arrays, and every
access to it requires one step of indirection.
Additionally, the use of binding arrays requires that, during trailing, both
the address of the variable and its current value are saved in the trail
stack (which doubles the cost of trailing/untrailing).
Tue Mar 19 14:37:09 MST 1996