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Subject: Re: [OMPI devel] Affect of compression on modex and launch messages
From: Roland Dreier (rdreier_at_[hidden])
Date: 2008-04-04 14:29:53


> 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.