Re: MPI_TYPE_DUP

Eric Salo (salo@mrjones.engr.sgi.com)
Fri, 13 Dec 1996 15:59:48 -0800

> 2) If you are going to constant integers as the user representation of
> MPI_DATATYPE (and MPI 1.1 pretty much forces you into this), then
> it's easy enough to make them indices into a table of
>
> struct
> {
> Implementation_attr_cache * cache;
> Implementation_datatype * datatype;
> };

Jim, in general I agree with what you are saying but the above text worries me.
The last thing we (well, at least I) want to do is force implementations to add
yet another layer of indirection/cruft to the critical path. Supporting
user-defined datatypes is costly enough already, let's please not make it any
worse!

-- 
Eric Salo         Silicon Graphics Inc.             "Do you know what the
(415)933-2998     2011 N. Shoreline Blvd, 8U-802     last Xon said, just
salo@sgi.com      Mountain View, CA   94043-1389     before he died?"