Thread: Quad Quad-cores
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Old 2008-03-24, 18:25   #7
SlashDude
 
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Aug 2002
Minneapolis, MN

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Quote:
Originally Posted by lycorn View Post
Have you performed, or are considering to perform, any test using the multithreading capabilities of the 25.x version of Prime95 (running a single LL test on multiple cores and see how well it scales)?
I didn't know about this!

Some quick numbers:

Running 1 test on 16 cores (on the HP DL580) runs at .020 seconds per iteration on an exponent in the 47,000,000 range. This has the box running at ~51% total.
Single test: (CPU Affinity set to run on first CPU - Each addition thread took the CPU's in order - 0,1,2,3,4,5...)
Code:
Cores  Iteration   Box%
16     .020 sec    51%
8      .022 sec    40%
7      .023 sec    36%
6      .024 sec    32%
5      .029 sec    26%
4      .029 sec    23%
3      .034 sec    18%
2      .037 sec    13%
1      .067 sec     7%
Code:
Single test: (CPU Affinity set to run on any)
Cores  Iteration   Box%
16     .024 sec    41-51%
8      .024 sec    31%
7      .046 sec    20%
6      .051 sec    18%
5      .055 sec    17%
4      .029 sec    25%
3      .035 sec    19%
2      .050 sec    13%
1      .067 sec     7%
Code:
Two tests: (CPU Affinity set to run on 0 and 8)
Cores  Iteration   Box%
16     .036 sec    52% (.045 sec on Worker #2)
8      .024 sec    80%
7      .025 sec    72%
6      .027 sec    64%
5      .031 sec    55%
4      .031 sec    46%
3      .036 sec    35%
2      .039 sec    25%
1      .067 sec    13%
Code:
Two test: (CPU Affinity set to Smart Assignments)
Cores  Iteration   Box%
16     .044 sec    56%
8      .045 sec    50%
7      .046 sec    45%
6      .038 sec    52%
5      .045 sec    43%
4      .034 sec    48%
3      .046 sec    34%
2      .051 sec    25%
1      .067 sec     13%
Code:
Two test: (CPU Affinity set to run on any)
Cores  Iteration   Box%
16     .048 sec    45-55%
8      .048 sec    44%
7      .046 sec    45%
6      .040 sec    50%
5      .045 sec    42%
4      .034 sec    50%
3      .049 sec    33%
2      .051 sec    25%
1      .067 sec    13%
Four tests: (CPU Affinity set to run on 0, 4, 8 and C)
Code:
Cores  Iteration   Box%
6      .050 sec    63% (.73 on Worker #2 and Worker #3)
5      .036 sec    57% (.153 on Worker #1 and .233 on Worker #3)
4      .043 sec    93%
3      .045 sec    70%
2      .045 sec    50%
1      .069 sec    25%
Let me know if you want any other multi-threaded tests run.
-SD
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