On Mon, 2006-11-27 at 16:45 -0800, Matt Leininger wrote:
> Has anyone testing OMPI's alltoall at > 2000 MPI tasks? I'm seeing each
> MPI task eat up > 1GB of memory (just for OMPI - not the app).
I gathered some more data using the alltoall benchmark in mpiBench.
mpiBench is pretty smart about how large its buffers are. I set it to
use <= 100MB.
num nodes num MPI tasks system mem mpibench buffer mem
128 1024 1 GB 65 MB
160 1280 1.2 GB 82 MB
192 1536 1.4 GB 98 MB
224 1792 1.6 GB 57 MB
256 2048 1.6-1.8 GB < 100 MB
The 256 node run was killed by the OOM for using too much memory. For
all these tests the OMPI alltoall is using 1 GB or more of system
memory. I know LANL is looking into optimized alltoall, but is anyone
looking into the scalability of the memory footprint?
> - Matt
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