On Wed, 11 Jun 2003, Joao Pestana Ferreira wrote:
> I'm using lam beta 7 and I thought I would get more speed comparing with
> the stable lam 6.5, when using gigabit Ethernet, but I'm getting the
> same results.
>
> I assume that I can only get more speed if I use another transport
> (other than TCP). What are the available transports? (I heard about an
> M-VIA ...)
LAM provides near-raw TCP performance for matched send/recv in both 6.5.9
and 7.0 (even on gigabit). There are some boundry cases where LAM 7.0
will perform better than 6.5.9 (such as unexpected receives), but these
are fairly hard to quantify and really not things you want to be doing in
normal situations.
We have introduced a Myrinet/gm transport engine with LAM 7.0, allowing
high bandwidth and low latency over the Myrinet interconnects. There have
also been some improvements to the shared memory RPIs that should increase
realized bandwidth on SMP linux machines for long messages.
In LAM 7.0 the available transports are:
- TCP (everyone's old friend)
- SYSV (shared memory locally, TCP off-node)
- USYSV (shared memory locally, TCP off-node)
- CRTCP (checkpointable TCP - you need some other packages for this to
work)
- GM (Myrinet support)
More information on all of these can be found in the User's Guide,
included with the LAM 7.0beta tarballs in the doc/ directory.
Hope this helps,
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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