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-   -   CFX and i7 (http://www.cfd-online.com/Forums/cfx/72094-cfx-i7.html)

zandi January 25, 2010 12:51

CFX and i7
 
Hi
would any one help me with using full capacity of an i7 system on cfx runs.
actually I use a system with an intel i7 920 cpu and 8 GB RAM and have cfx 11
but I just can use 4 cores on my runs and it gives errors due to licence if I'm right.
thanks

Michiel January 26, 2010 03:52

I assume Ansys CFX has the same license configuration as the Mechanical modules. In that case the number of cpu's is limited at 2 for one license. If you want to use 4 cpu's you should buy a second license.

zandi January 26, 2010 11:29

Hi
thank you
I can get run with 4 core but not 8
would you please tell me if I have buy license for 8 or for 4 to run with 8 core of an i7
thanks again

ghorrocks January 26, 2010 17:34

You will need to buy additional licenses to run 8 processes. But don't bother. The I7 chip has 4 cores so running any more processes on it is bad. It looks like 8 processes on task manager as each core looks like 2 cores due to hyperthreading - but CFX does not take advantage of hyperthreading so you do not gain a useful speedup by using 8 cores.

Unless you have a dual CPU system, then you do have 8 cores. Then you just need to get that many licenses to run it.

zandi January 27, 2010 05:56

Quote:

Originally Posted by ghorrocks (Post 243818)
You will need to buy additional licenses to run 8 processes. But don't bother. The I7 chip has 4 cores so running any more processes on it is bad. It looks like 8 processes on task manager as each core looks like 2 cores due to hyperthreading - but CFX does not take advantage of hyperthreading so you do not gain a useful speedup by using 8 cores.

Unless you have a dual CPU system, then you do have 8 cores. Then you just need to get that many licenses to run it.

I appreciate your useful helps
Would you please say how I can understand that a system is dual cpu system or not?
What do you mean by many licenses exactly?
Thank you

ghorrocks January 27, 2010 16:51

Did you get a computer with 1 CPU or 2? If you can't answer this then open the box and have a look!

Parallel licenses are per-process. You need 8 to run an 8-way parallel job but only 4 to run a 4 way parallel job.

zandi January 28, 2010 03:49

Quote:

Originally Posted by ghorrocks (Post 243959)
Did you get a computer with 1 CPU or 2? If you can't answer this then open the box and have a look!

Parallel licenses are per-process. You need 8 to run an 8-way parallel job but only 4 to run a 4 way parallel job.


thanks a lot friend

sazabi2001 June 4, 2010 11:01

I guess hyper threading may help....very little bit of CFD formance. It won't worth the price of licensing for the extra 4 virtual cores and just get less than 20% improvement.


Take a look this:
http://techreport.com/articles.x/18581/14

ghorrocks June 5, 2010 05:31

CFX has not been complied to use hyperthreading. Don't use it. Just leave the virtual cores sit idle or even better disable them in the BIOS.


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