Newsgroups: comp.parallel
From: butenuth@i30s23.ira.uka.de (Roger Butenuth)
Subject: Re: Highly Efficient Collective Communication on Paragon
Organization: University of Karlsruhe, Germany
Date: 9 Mar 1995 14:04:58 GMT
Message-ID: <3jqf1m$58v@usenet.srv.cis.pitt.edu>

In article <3jkn8n$i05@usenet.srv.cis.pitt.edu> rvdg@cs.utexas.edu
(Robert van de Geijn) writes:

|>                   vector        NX        InterCom      ratio
|>     Operation     length       (sec)       (sec)     (NX/InterCom) 
|>   -----------------------------------------------------------------
|>
|>     Broadcast     8 bytes      0.0017      0.0014        1.21
|>                 64K bytes      0.0356      0.0069        5.18
|>                  1M bytes      0.5788      0.0493       11.75
|>
|>   Global Sum      8 bytes      0.0032      0.0029        1.10
|>     to all      64K bytes      0.3780      0.0195       19.35 
|>                  1M bytes      5.9353      0.1791       33.15

We were surprised about this performance data, because the operating
system Cosy (Concurrent Operating SYstem) with the Library PIGSeL is
about as fast as the Paragon, considerung it is running on Transputers
(T805, 30MHz), with only 30 MIPS / 2 MFLOPS / 1.7 MB/s bandwith on its
links.

The performance on the Paragon should be at least an order of
magnitude better than on Transputers, an more than five years old
architecture. 

We did our measurements on the GCel1024 in Paderborn with 16 x 32
processors in a grid topology (half of the machine) and want to thank
the PC^2 for giving us this opportunity.


                    vector        NX        InterCom      Cosy
      Operation     length       (sec)       (sec)        (sec)
    -------------------------------------------------------------
 
    Global Sum      8 bytes      0.0032      0.0029      0.0062
      to all                                             ======


|>For more information, access 
|> 
|>    http://www.cs.utexas.edu/users/rvdg/intercom

For more information about Cosy, access

       http://i30www.ira.uka.de/projects/cosy/index.html

Or mail to

	butenuth@ira.uka.de   (Cosy)
	sanders@ira.uka.de    (PIGSeL)

Roger Butenuth and Peter Sanders


