CFX and i7

zandi · January 25, 2010, 12:51

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

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

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, 12:01

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, 06:31

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.

January 25, 2010, 12:51	CFX and i7	#1
zandi Senior Member Fatema Zandi Goharrizi Join Date: Mar 2009 Posts: 158 Rep Power: 17	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

June 5, 2010, 06:31		#9
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	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. Whitebear likes this.

January 26, 2010, 03:52		#2
Michiel Member Michiel Join Date: Jul 2009 Location: The Netherlands Posts: 42 Rep Power: 17	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.

January 26, 2010, 11:29		#3
zandi Senior Member Fatema Zandi Goharrizi Join Date: Mar 2009 Posts: 158 Rep Power: 17	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

January 26, 2010, 17:34		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	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.

January 27, 2010, 16:51		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	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.

June 4, 2010, 12:01		#8
sazabi2001 New Member YongQiang Chi Join Date: Jun 2010 Posts: 14 Rep Power: 16	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