[Beowulf] Maximizing intra-node communication performance

[Jakob Oestergaard]

On Tue, Dec 27, 2005 at 12:05:55PM +0200, Tahir Malas wrote:
> Hi all,
> Taking advice from a previous discussion, we have purchased an Tyan server
> with 8 dual-core Opteron 870 processors. Now I want to wonder how I can
> maximize the intra-node communication of the server. We have been using
> LAM-MPI, but I think that TCP/IP protocol may degrade the performance. Has

When Linux does TCP on the local host only, that should be very very
efficient (the kernel can make a lot of shortcuts and it does).

Of course, there are more efficient ways, but I wanted to say that TCP
on the local host is quite different performance wise that TCP over an
actual external network.

> anybody tried new implementations of MPI, or anybody knows some other
> support for intra-node communication?

Can't you tell MPI to use shared memory?  (I'm sure that I used an MPI
that allowed that - I think all I had to do was set an environment
variable - but this is a long time ago and I don't remember the details
exactly).

-- 

 / jakob