CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLOW-3D

F3D v9.3

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   April 15, 2009, 13:27
Default F3D v9.3
  #1
New Member
 
Armen
Join Date: Apr 2009
Posts: 2
Rep Power: 0
argir is on a distinguished road
Hi everyone. I am using F3D v.9.3 SMP on Core i7 platform. I am comparing CPU usage on Core 2 Duo and Core 2 Quad. The CPU usage on Core 2 Duo and Core 2 Quad is 100% but on Core i7 CPU usage is 60-70%. Could anyone explain why?

PS. I am also using MP version on two Xeon Quad and it is using 100% of CPUs.
argir is offline   Reply With Quote

Old   April 15, 2009, 14:31
Default
  #2
H.C
Member
 
Join Date: Mar 2009
Posts: 40
Rep Power: 8
H.C is on a distinguished road
are you running the same input files on all machines? how many cores did you specify in the input files? The core i7 machine might have hyper-thread tech, and if there are 4 cores, the windows will think it has 8 cores. That might be the reason why you only see 60% or 70% on i7 machine.
H.C is offline   Reply With Quote

Old   April 15, 2009, 15:11
Default
  #3
New Member
 
Armen
Join Date: Apr 2009
Posts: 2
Rep Power: 0
argir is on a distinguished road
Of course I am using the same prepin file and stl file. I am using “All available processors” so it shows 8 processors in solver. I was thinking that it could be due to RAM but 6Gb is quite enough. Do you mean that Core i7 is only 10-20% faster than Core 2 Quad? But here is another question why the CPU usage is not 100%. I am conceding that Core i7 is not two times faster but F3D is not using 100% of CPU? Is it due to unoptimized architecture? (I read about that (couple mathematical software) in reviews)
argir is offline   Reply With Quote

Old   April 15, 2009, 18:11
Default
  #4
H.C
Member
 
Join Date: Mar 2009
Posts: 40
Rep Power: 8
H.C is on a distinguished road
As mentioned, becoz of the hyper-thread tech, even though windows reports that there are 8 cores, it only has 4 real cores, and as flow3d is a computationally intensive program, the 4 real cores will be fully occupied during a simulation and the other 4 hyper-thread cores normally don't have much chance to be utilized. That's probably why it cannot reach 100% usage sometimes.

As for how faster the core i7 is compared to core2 quad, I dont many details, and more info on the CPU codes is needed. But for some certain case setup (with the same numerical method and number of cores), it was noticed that core i7 965 can be 2x faster than core2 quad Q9650.
H.C is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Export in F3D Ali FLOW-3D 5 December 4, 2008 01:42
Simulation VIDEO issue in v9.3 Nikolaos FLOW-3D 4 October 2, 2008 09:10


All times are GMT -4. The time now is 19:05.