[Beowulf] programming multicore clusters
gerry.creager at tamu.edu
Fri Jun 15 12:10:11 PDT 2007
Greg Lindahl wrote:
> On Fri, Jun 15, 2007 at 08:00:24AM -0500, Gerry Creager wrote:
>> For the forseeable future, I'm not developing much but will use the
>> hybrid SMP/DM capabilities in WRF. Takes advantage of SMP availability,
>> and supports message passing between SMP nodes. I've not used this
>> capability for benchmarking but it appears to offer significant gains.
> Gerry, why do you think WRF is going to behave any different from MM5
> in this aspect? MM5 slows down in hybrid mode. MPI "takes advantage"
> of SMP. In fact, on big SMPs like Origin and Altix, MPI programs are
> often faster than shared memory or OpenMP programs, unless you've done
> a lot of work on the OpenMP program to improve locality. Why? Because
> you're forced to worry about locality in an MPI program all the time.
Potentially false advertising. NCAR/MMM are of the opinion that it runs
faster. I've not tested it yet...
>> As we get more hybrid HPC capabilities planning for this will be more
> I predict a lot of people will waste a lot of time without seeing a
Gerry Creager -- gerry.creager at tamu.edu
Texas Mesonet -- AATLT, Texas A&M University
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983
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