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immortality July 6, 2013 09:43

is 4170 a 4 core cpu or 2 core?cores or threads?
according to lscpu Fx-4170 has only 2 cores and 4 can judge about it?threads are like cores in calculating?

ehsan@Ehsan-com:~$ lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                4
On-line CPU(s) list:  0-3
Thread(s) per core:    2
Core(s) per socket:    2
CPU socket(s):        1
NUMA node(s):          1
Vendor ID:            AuthenticAMD
CPU family:            21
Model:                1
Stepping:              2
CPU MHz:              1400.000
BogoMIPS:              8399.94
Virtualization:        AMD-V
L1d cache:            16K
L1i cache:            64K
L2 cache:              2048K
L3 cache:              8192K
NUMA node0 CPU(s):    0-3

CapSizer July 6, 2013 18:49

1 Attachment(s)
The current series of AMD CPU's use a slightly unusual design. The CPU's are built up from a number of "modules", each of which has two cores that share a single floating point processor. You can get into long debates about whether or not this is a brilliant way of putting together a CPU, but in fact it makes quite a lot of technical sense, even if it is not great for CFD use. Your 4170 CPU has two of these modules, therefore 4 cores in total, but only two floating point processors. This may not be as bad as it sounds. You can run 4-way parallel, and it will be significantly faster than running just two way parallel, but will probably not be twice as fast. What you should do is to run exactly that test ... set up an OpenFOAM case, and run it serial, 2-way, 3-way and 4-way. Then graph the number of iterations / minute, and post the graph here.

The attached graph should help explain - this is an "8-core" FX8150. Once you get to 4-way parallel, the speed flattens off, because you now have to start sharing floating point processors. You also get a saturation of the memory system, which is less noticeable when you underclock it.

immortality July 7, 2013 03:53

How can estimate iterations/minute?
And use Calc for drawing or gnuplot?

wyldckat July 7, 2013 08:52

Greetings to all!

@Charles: Many thanks for the clarification! I had a firm belief that AMD hadn't lowered themselves to using HT-like technology to boost their sales, but I guess I was wrong:
According to the link above, it means that there is only 80% performance if there were 4 actual cores :( It's not as bad as HT, but still...

@Ehsan: Based on the link above an this link: - I would estimate that your CPU should do roughly 50% of the number of iterations as of Charles' 8150 CPU.
And I believe he used Open/Libreoffice Calc.

Best regards,

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