Re: a (radical ?) alternative to current chapter 4

James Cownie (jcownie@bbn.com)
Tue, 02 Jul 1996 14:28:07 +0100

Marc,

You have MPI_WINDOW_LOCK (a blocking lock acquisition call)
You have an MPI_WINDOW_TRYLOCK which returns true or false (as the
current MPI_IPROBE).

Don't you also want an MPI_WINDOW_ILOCK which returns a request which
one can later test or wait on ?

The request completes once the lock is claimed by this call. Such a
call would allow non-busy waiting for a lock, which is not possible
with the current calls.

Of course this may have implementation implications (like requiring a
global queue of lock requests somewhere.)

Also you say nothing about fairness of lock acquisition. (This may be
deliberate :-) ). Somwehere I think we should say something, even if
it is only that no fairness guarantees are given.

-- Jim

James Cownie
BBN UK Ltd
Phone : +44 117 9071438
E-Mail: jcownie@bbn.com