actually, we used lzo a looong time ago with PACX-MPI, it was indeed
faster then zlib. Our findings at that time were however similar to what
George mentioned, namely a benefit from compression was only visible if
the network latency was really high (e.g. multiple ms)...
Thanks
Edgar
Roland Dreier wrote:
> Based on some discussion on this list, I integrated a zlib-based compression
> ability into ORTE. Since the launch message sent to the orteds and the modex
> between the application procs are the only places where messages of any size
> are sent, I only implemented compression for those two exchanges.
>
> I have found virtually no benefit to the compression. Essentially, the
> overhead consumed in compression/decompressing the messages pretty much
> balances out any transmission time differences. However, I could only test
> this for 64 nodes, 8ppn, so perhaps there is some benefit at larger sizes.
A faster compression library might change the balance... eg LZO
(http://www.oberhumer.com/opensource/lzo) might be worth a look although
I'm not an expert on all the compression libraries that are out there.
- R.
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--
Edgar Gabriel
Assistant Professor
Parallel Software Technologies Lab http://pstl.cs.uh.edu
Department of Computer Science University of Houston
Philip G. Hoffman Hall, Room 524 Houston, TX-77204, USA
Tel: +1 (713) 743-3857 Fax: +1 (713) 743-3335
