Re: Tasking Models

["Marin D. Condic" <mcondic-nospam@quadruscorp.com>]

Marin D. Condic wrote:
> In the past, when I've cared to find out about it, Ada compilers I've
> run under various operating systems do not block on an I/O or other
> sorts of OS calls. I know this is legal behavior. I don't know of any
> reason why it would be *illegal* for the RTK to consider a task blocked
> on an OS call. This would be desirable behavior under lots of

And speaking of task blocking, OS blocking and timeslicing.....

Can anybody tell me about the behavior of GNAT in these areas? I have
attempted some GNAT/TCP/IP stuff under Win98 and the behavior when tasks
are involved seems to be that the RTK does not recognize that a thread
is blocked when a call is made to TCP/IP. (Other tasks starve). Is this
the same behavior one could expect under WinNT? How about under various
flavors of Unix? Is there some sort of pragma that can be set which
would insist that the RTK use a timeslicing model? (Except for possible
performance issues, this at least can get you around tasks that are
blocked for I/O.)

It might be interesting to take some of the current software I'm working
with and run it through GNAT to see if that would solve some of our
troubles. But before I go unhooking all the system dependencies for a
new compiler, it would be nice to know about how the RTK handles these
things.

Maybe this is all answered in the Super Secret GNAT Documentation, but
perhaps someone will be kind to the lazy and ignorant? :-)

MDC
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Marin David Condic - Quadrus Corporation - http://www.quadruscorp.com/
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