[vox-tech] mmap()

[Norm Matloff]

> From: Bill Broadley <bill at broadley.org>

> I've minimal experience with Rmpi.  But sub 2us MPI wasn't hard even 7 
> years ago.  Trying to do app -> mmap -> nfs client -> nfs server -> nfs 
> client -> mmap and I'd be impressed with sub 2ms (a factor of 1000 
> slower).  Does RMPI do anything stupid like assume TCP over ethernet?

As I mentioned, I'm willing to give up some performance for portability.
We're not talking about Infiniband here.  The primary use of Rdsm is for
multicore machines, not clusters, but I wish to have some usability on
cluster platforms, on which at least large-granularity problems should
work OK.

In the parallel processing world, there is always a tradeoff between
performance and convenience.  If convenience were not an issue, then no
one would even attempt to do parallel code in R or Python; we'd write
all our code in assembly language. :-)

Rmpi uses whatever MPI gives it.  If you have MPI configured in whatever
specialized way, Rmpi uses it.

Norm