Re: Tasking in Ada

[howland.reston.ans.net!wupost!cs.utexas.edu!utnut!utcsri!csri.toronto.edu !blaak@gatech.edu (Raymond Blaak)]

kgatlin@galaxy.csc.calpoly.edu (Kang Su Gatlin) writes:

>I have hit a snag with Ada.  I need to create dynamic tasks that know which
>task they are.
...
>I can't seem to find a way to pass information to tasks efficiently.  I want
>all the tasks to run simultaneously so that the creation and execution of
>the tasks can be done in t(1) time.  

>The only way I can think of how to do it is to loop through and create the 
>tasks but that is O(n) time.  Or I can create an array of tasks (if that is
>possible) but then how do I get information to the tasks with using the
>rendezvous mechanism (again O(n)).

If n is small, then looping through is probably the best way. If n is large
then consider the array of tasks as a tree (i.e. the children of task i are
tasks 2i and 2i+1) and have each task communicate the identities to its
children. This would give you O(log n) time. To start things off you would
need only to tell task 1 its identity.

At any rate, if your code is running on a serial machine, then simply looping
through is faster anyway, for there would be less parallelism being simulated
to assign the identities.

Cheers,
Ray
blaak@csri.toronto.edu