[Beowulf] Thought that this might be of interest

Richard Walsh rbw at ahpcrc.org
Mon Nov 6 10:08:02 EST 2006


Joe Landman wrote:
> We are working on a machine with 2 Opteron 2218s.  For laughs, I ran 
> streams on it.  Here are 1,2,3,4 processor data.
>
> 1 processor:
>
> Copy:       5713.9944      0.0591      0.0560      0.0600
> Scale:      5713.9822      0.0587      0.0560      0.0600
> Add:        5454.2389      0.0911      0.0880      0.0920
> Triad:      5454.1576      0.0916      0.0880      0.0920
>
     Mmmm ... these actually seem low considering the bus bandwidth is 
supposed to be 10.67 GB/sec
     in the socket F.  Using the 75% rule (1 silent read, 2 actual 
reads, and 1 write) from the triad shouldn't
     we get:

     10.67 * .75 =  ~8 GBs/sec
>
> 2 processors:
>
> Function     Rate (MB/s)  Avg time   Min time  Max time
> Copy:       5713.8788      0.0591      0.0560      0.0640
> Scale:      5713.9822      0.0596      0.0560      0.0640
> Add:        5713.9538      0.0858      0.0840      0.0880
> Triad:      5713.9538      0.0871      0.0840      0.0880
>
>
> 3 processors:
>
> Copy:       8888.4000      0.0391      0.0360      0.0400
> Scale:      8888.4147      0.0391      0.0360      0.0400
> Add:        8570.9733      0.0573      0.0560      0.0600
> Triad:      8570.9551      0.0587      0.0560      0.0600
>
>
> 4 processors:
>
> Copy:      11428.1834      0.0293      0.0280      0.0320
> Scale:     11428.1347      0.0298      0.0280      0.0320
> Add:       10908.5812      0.0449      0.0440      0.0480
> Triad:     10908.6107      0.0440      0.0440      0.0440
     Mmm ... similarly ... this seems to be only 50% of the full bandwidth
     of 2 socket F buses?  
> I did get one outlier at 4 CPUs.  Could be a timing glitch.
>
> 4 processors:
> Copy:      13332.7765      0.0302      0.0240      0.0360
> Scale:     13332.7765      0.0262      0.0240      0.0320
> Add:       13332.6220      0.0400      0.0360      0.0480
> Triad:     14999.0756      0.0391      0.0320      0.0480
     These are the numbers I would expect here  ... about 70% of  2 * 
10.67 GBs/sec.
     I think that your out-"liar" is actually giving you the correct 
numbers.
>
> This is a dual socket 1207 motherboard.  DDR2/533 ECC Registered 
> memory (will look back and check to be sure).
>
> Initial benchmarks (2.6 GHz clock) put it at about 17% faster than 
> Opteron 275 and Woodcrest 5150 (2.66 GHz) on a GAMESS test we use 
> (1h41m for Woodcrest and 275, and 1h26m for this unit).
     AMDs premium socket F is the 2220 SE which runs at 2.8 GHz.  The 
new AMD 4 digit naming convention
     is discussed in the presentation I posted earlier.

     rbw


-- 

Richard B. Walsh

"The world is given to me only once, not one existing and one
 perceived. The subject and object are but one."

Erwin Schroedinger

Project Manager
Network Computing Services, Inc.
Army High Performance Computing Research Center (AHPCRC)
rbw at ahpcrc.org  |  612.337.3467

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