On Sep 15, 2004, at 10:25 AM, Dominique Lucas wrote:
> I have installed lam/mpi version 7.0.6 on our IBM SP4+ system with HPS
> (High Performance Switch) which is rated at 2GB/sec.
> With the native MPI implementation, we achieve transfers rated
> at about 1.7GB/sec. With lam/mpi, I reach only 550MB/s.
>
> On our "old" SP4 system, with PCI switch - rated at 375MB/sec -
> lam/mpi version 7.0.3. reached more than 350MB/s which was comparable
> to the native MPI implementation on that system.
>
> Is there any way to tune lam/mpi for SP4+ systems with HPS?
So the native MPI implementation is going to be using the LAPI
interface as opposed to TCP to achieve 17Gb/s. LAM/MPI does not
support LAPI (the native layer for IBM SP systems), so we have to use
TCP. TCP over LAPI or GigE (depending on how you are routing things)
should theoretically hit a bit under a gigabit/sec if you really tune.
550Mb/s is ballpark reasonable if the TCP implementation isn't heavily
optimized.
In short, there really isn't much you can do with the current release
of LAM/MPI. In the future, we intend to look at native LAPI support,
but we can't offer a time table for that support.
Brian
--
Brian Barrett
LAM/MPI developer and all around nice guy
Have a LAM/MPI day: http://www.lam-mpi.org/
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