[Beowulf] Woodcrest Memory bandwidth

Jason Holmes jholmes at psu.edu
Mon Aug 14 15:18:00 EDT 2006


Mark Hahn wrote:
>> Here's a 4 core Woodcrest system with 4 sticks of 2 GB 667 MHz FB-dimms:
>>
>> Function     Rate (MB/s)  Avg time   Min time  Max time
>> Copy:       4813.2590      0.2663      0.2659      0.2675
>> Scale:      4826.2181      0.2656      0.2652      0.2662
>> Add:        5244.0135      0.3664      0.3661      0.3669
>> Triad:      5244.3106      0.3665      0.3661      0.3671
>>
>> This was a pathscale compiled stream executable with openmp using 4 
>> threads.
> 
> kinda sucks, doesn't it?  here's what I get for a not-new dual-275 with 
> 8x1G PC3200 (I think):
> 
> Function      Rate (MB/s)   RMS time     Min time     Max time
> Copy:        5714.6837       0.0840       0.0840       0.0841
> Scale:       5821.0766       0.0825       0.0825       0.0826
> Add:         6437.8226       0.1119       0.1118       0.1120
> Triad:       6414.2079       0.1123       0.1123       0.1124

Bill and I passed a few emails off the list and it seems that he's heard 
reports of up to 10 GB/s.  I tried on 2 different Woodcrest systems (one 
from Dell, one directly from Intel) here and they both report back 
similar numbers.  It seems that the fortran version of the program with 
pathscale 2.3 (the numbers I reported above) reports different numbers 
than the C version of the program with pathscale 2.3:

Function      Rate (MB/s)   Avg time     Min time     Max time
Copy:        6129.2441       0.2090       0.2088       0.2097
Scale:       6138.1509       0.2087       0.2085       0.2091
Add:         5935.6727       0.3236       0.3235       0.3237
Triad:       5972.4347       0.3217       0.3215       0.3221

and the C version with Intel 9.1:

Function      Rate (MB/s)   Avg time     Min time     Max time
Copy:        6145.6340       0.2084       0.2083       0.2090
Scale:       4830.1172       0.2652       0.2650       0.2658
Add:         5289.7542       0.3632       0.3630       0.3638
Triad:       5296.5246       0.3629       0.3625       0.3640

Thanks,

--
Jason Holmes
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