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Juan Catelén August 16, 2007 09:59

AMD processor
Hello. I have a computer with an AMD opteron 64 bit processor. Each core is subdivided, so it works as if I had four processors. As I have a single license for cfx I'm loosing a lot of power to make runs. How can I change this? Thanks in advance.

CycLone August 16, 2007 10:12

Re: AMD processor
Purchase 4 parallel process licenses.

Robin August 16, 2007 10:30

Re: AMD processor
Hi Juan,

It doesn't just work "as if" you had four processors; a core IS a processor. The only difference is that they put more of them on a chip (which we all used to associate with processors). This is more inexpensive for the the chip manufacturers than producing multiple chips. Unfortuntately they also have to share the memory bandwidth of the chip.

As suggested, you'll need parallel licenses to run on all 4 cores.

Regards, Robin

Juan Catelén August 16, 2007 10:39

Re: AMD processor
Can I make each dual core to work as one instead of divided?

CycLone August 16, 2007 11:23

Re: AMD processor
No, as Robin points out, each core is in fact a separate processor, they are just assembled on a single chip instead of separate chips. For software to run on multiple cores it still needs to be written or work differently. There are basically two ways to use multiple cores: thread the code, or parallelize it.

Threading is very common and it allows the application to essentially farm out individual operations or "threads" which the OS can assign to one processor or another. This works fine for many common applications such as databases, games and word processors; these are not computationally expensive and the individual tasks are not strongly dependant.

Computational codes such as CFD or FEA software cannot be parallelized this way (at least not the time consuming portions). CFX runs in parallel by launching multiple solver executables, one per partition (and usually one per core or processor, but multiple executables can run on the same processor). The solver processes then exchange data and bla, bla, bla; you get the point.

Anyway, the long and short of it is that you need to purchase parallel licenses to enable this capability. They are only a fraction of the price of a solver though, so it shouldn't be a hard to justify.


bob August 28, 2007 06:13

Re: AMD processor
alternatively, swap the quad-core for a higher clock speed single core or dual-core cpu, they are 20-30% faster than quad-cores

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