p4 v itinium

[Troy Baer]

On Tue, 14 May 2002, Ricky Rankin wrote:
> I am currently looking to setup a linux cluster for use by 
> researchers in the University. I would appreciate any views on 
> the following:-
> 
> can a p4 access more than 4GB memory - some of the codes have a 
> requirement to access large memory

A single process on any x86 can only access 2-3 GB of memory under
Linux without resorting to heroic measures, as far as I know.

> if I have to go to itanium, is there a reliable fortran compiler 
> for this platform

We've been using the Intel Fortran compiler (efc) on our Itanium cluster,
and it's definitely usable, at least some long as you have bog-standard
Fortran 77 or 90.  It doesn't seem to like many of the common extensions
(eg. Cray-style pointers), though.  gcc and friends on Itanium are dogs.

> if p4 can access greater than 4GB memory are there any 
> preformance gains in going for the more expensive itanium option

For floating-point intensive codes, I've found an Itanium 733MHz is
roughly as fast as a 1.4GHz Athlon; I wouldn't expect a P4 to be much
faster than that, based on the benchmarks I ran last summer.

	--Troy
-- 
Troy Baer                       email:  troy at osc.edu
Science & Technology Support    phone:  614-292-9701
Ohio Supercomputer Center       web:  http://oscinfo.osc.edu