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Subject: Re: [OMPI devel] Affect of compression on modex and launch messages
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2008-04-04 14:36:12


LZO looks cool, but it's unfortunately GPL (Open MPI is BSD). Bummer.

On Apr 4, 2008, at 2:29 PM, 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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-- 
Jeff Squyres
Cisco Systems