CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > CFX

CPU time Vs Wall clock time

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   February 26, 2012, 00:06
Unhappy CPU time Vs Wall clock time
  #1
HMR
Member
 
HMR
Join Date: Jan 2011
Posts: 31
Rep Power: 15
HMR is on a distinguished road
Dear CFX users ,

In my one desktop(windows7), processor 1.86Ghz, RAM 4 GB, 64bit OS, I am trying to do a simulation with 1.6 million mesh. I have found that last 2days ago I start a transient simulation at night around 7 ‘ o clock and when I came back nextday at my workplace 9’o clock morning and found that it is completed only 17 time steps in last 14 hrs . Moreover I have checked that the total cpu time and total wall clock time is not same in CFX solver manager.


Same simulation I started yesterday at day time watch what happened and saw that full simulation take 8 hrs to finish 400 time step but every hour I have checked whether simulation is working or not.



Today still same problem occured after certain time period I think simulation stopped and whenever I check simulation , move cursor then it starts calculation. Additionally I have checked that during simulation run time CPU usages showing 50% and physical memory is showing 35% in this dual core machine.


I am confused why this is happening because in my another desktop with windows XP, 3.25Gb RAM, if I start any simulation(400,000 mesh) and checked that it is finished all time step without any problem, I mean it is not idle.

Is this problem arises from my this system or anything need to change in windows 7.


If anybody help me to find out the problem then it would be good for me.


Thanks



HMR
HMR is offline   Reply With Quote

Old   February 26, 2012, 04:06
Default
  #2
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,703
Rep Power: 143
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
Most probably you have filled the physical RAM and it is using the page file (hard drive). This is far slower than physical RAM so the simulation will proceed very slowly. When you start a new run you should look at the task manager (or top for the linux types) to check the run starts OK and grabs a full CPU worth of power. If the CPU load is struggling then you probably have run out of RAM.
ghorrocks is offline   Reply With Quote

Old   February 28, 2012, 19:06
Default
  #3
HMR
Member
 
HMR
Join Date: Jan 2011
Posts: 31
Rep Power: 15
HMR is on a distinguished road
Thanks Glenn for your quick advice. Sounds like I need to change my system configuration mainly RAM.

Regards

HMR
HMR is offline   Reply With Quote

Reply


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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
[Commercial meshers] Fluent3DMeshToFoam simvun OpenFOAM Meshing & Mesh Conversion 50 January 19, 2020 15:33
Natural convection in a closed domain STILL NEEDING help! Yr0gErG FLUENT 4 December 2, 2019 00:04
Full pipe 3D using icoFoam cyberbrain OpenFOAM 4 March 16, 2011 09:20
Multicomponent fluid Andrea CFX 2 October 11, 2004 05:12
On the reduction of cpu time lee Main CFD Forum 4 March 7, 1999 22:02


All times are GMT -4. The time now is 15:02.