CPU Time

MissCFD · June 21, 2015, 17:13

How can I recover data about CPU Time written in .out file especially when it is a parallel simulation ?

What time is exactly taken into account in calculation of CPU Time ?

Thank you

ghorrocks · June 21, 2015, 18:49

The wall clock and CPU time is listed in the output file after the solution iterations and again at completion of the simulation.

The CPU time is the time the CPU has been processing. It is a system measured parameter - have a look at task manager, it is the time taken by the CFX process.

The important thing about CPU time is that if the CPU time is small compared to the wall clock time then the simulation spent a lot of time doing things other than processing the simulation. Usually this means you ran out of memory and it had to write lots of swap files. This greatly degrades the simulation speed so is best avoided.

June 21, 2015, 17:13	CPU Time	#1
MissCFD Senior Member Join Date: Aug 2014 Posts: 160 Rep Power: 11	How can I recover data about CPU Time written in .out file especially when it is a parallel simulation ? What time is exactly taken into account in calculation of CPU Time ? Thank you

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June 21, 2015, 18:49		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	The wall clock and CPU time is listed in the output file after the solution iterations and again at completion of the simulation. The CPU time is the time the CPU has been processing. It is a system measured parameter - have a look at task manager, it is the time taken by the CFX process. The important thing about CPU time is that if the CPU time is small compared to the wall clock time then the simulation spent a lot of time doing things other than processing the simulation. Usually this means you ran out of memory and it had to write lots of swap files. This greatly degrades the simulation speed so is best avoided.