[Beowulf] Woodcrest Memory bandwidth

Jason Holmes jholmes at psu.edu
Mon Aug 14 16:03:41 EDT 2006


Mark Hahn wrote:
>> 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:
> 
> my numbers were from a random stream binary I had around,
> so I don't really even remember which compiler for sure
> (probably pathscale 2.2.1, may well have been C rather than fortran).
> 
> recompiling with a fresh copy of the source gives me 9.4 GB/s
> on my dual-socket single-core opteron 2.6 cluster, and 8.8
> or so on the aforementioned 2x2 (275).

Interesting.  I just ran the same stream binary I was using on the 
Woodcrest systems on a few Opterons here, all of which should be running 
DDR400:

1) dual-socket, single-core 2.4 GHz Opteron

Function      Rate (MB/s)   Avg time     Min time     Max time
Copy:        7776.2299       0.0041       0.0041       0.0042
Scale:       7808.8043       0.0041       0.0041       0.0041
Add:         7363.0030       0.0065       0.0065       0.0065
Triad:       7342.8621       0.0065       0.0065       0.0066

2) quad-socket, single-core 2.6 GHz Opteron

Function      Rate (MB/s)   Avg time     Min time     Max time
Copy:       18464.4006       0.0017       0.0017       0.0017
Scale:      17838.6135       0.0018       0.0018       0.0018
Add:        17937.1518       0.0027       0.0027       0.0027
Triad:      17910.0251       0.0027       0.0027       0.0027

3) quad-socket, dual-core 2.4 GHz Opteron

Function      Rate (MB/s)   Avg time     Min time     Max time
Copy:       16048.9929       0.0020       0.0020       0.0020
Scale:      16087.4659       0.0020       0.0020       0.0020
Add:        15650.3881       0.0031       0.0031       0.0031
Triad:      15574.1156       0.0031       0.0031       0.0031

So I think my binary is probably OK.  I used "pathcc -Ofast -mp stream.c 
-static -o stream_omp.x86_64".

Thanks,

--
Jason Holmes

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