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CPU usage

Posted 06.11.2011, 12:54 GMT-5 7 Replies

Meysam Najari
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Hello,

I am modeling a problem with 4equations coupled with each other leading to 50000 degrees of freedom. My system has CPU i7 with 8 cores and 12 MB of RAM. The problem is that when I check the performance of CPUs from windows task manager I see that there is 90% of load on one core and about 20~30% of load on the others. I was wondering how I could put load on all of the cores to get faster modelling. The affinity is on all the cores and the priority is on high.

Thanks,

Meysam
7 Replies Last Post 11.01.2012, 10:57 GMT-5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 06.11.2011, 14:17 GMT-5
Hi

I suppose you mean 12GB of ram ;)

For the loading distribution I do not believe you can change much; in V4, COMSOL will take as many CPUs as awailable.

But, not all tasks might be parallelised, and not all CPU can access the RAM simultaneously, depending on the RAM size, cash size, the RAM bandwidth and your hardware, so some, or all, CPUs might be in "wait state" ;)

I usually only run half the cores awailable (with the -np12 command switch, I have 24 cores) because I have noticed I gain little for my solving speed to use more, but then at least the PC is still responsive for me to see what is hapenning. Except if it starts to swap, then the PC freezes, so stay within awailable RAM if you want to see the results once ;)

--
Good luck
Ivar
Hi I suppose you mean 12GB of ram ;) For the loading distribution I do not believe you can change much; in V4, COMSOL will take as many CPUs as awailable. But, not all tasks might be parallelised, and not all CPU can access the RAM simultaneously, depending on the RAM size, cash size, the RAM bandwidth and your hardware, so some, or all, CPUs might be in "wait state" ;) I usually only run half the cores awailable (with the -np12 command switch, I have 24 cores) because I have noticed I gain little for my solving speed to use more, but then at least the PC is still responsive for me to see what is hapenning. Except if it starts to swap, then the PC freezes, so stay within awailable RAM if you want to see the results once ;) -- Good luck Ivar
Meysam Najari
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Posted: 1 decade ago 06.11.2011, 14:40 GMT-5
Thanks Ivar :); it seems there is no way to make the simulation faster with the current computer of mine. I have a question though. My drive C is almost full. doesnènt it affect the speed of simulationÉ

Thanks

Meysam
Thanks Ivar :); it seems there is no way to make the simulation faster with the current computer of mine. I have a question though. My drive C is almost full. doesnènt it affect the speed of simulationÉ Thanks Meysam
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 06.11.2011, 15:48 GMT-5
Hi

clear that a full disk can slow down everything from the OS to comsol, and even freeze a simulation. There are a few tools in Windows OS to clean up, but be careful with what you delete, always have a backup ;)

--
Good luck
Ivar
Hi clear that a full disk can slow down everything from the OS to comsol, and even freeze a simulation. There are a few tools in Windows OS to clean up, but be careful with what you delete, always have a backup ;) -- Good luck Ivar
Meysam Najari
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Posted: 1 decade ago 06.11.2011, 17:27 GMT-5
Thanks again Ivar :) I tried disc cleanup and deleted 15 GBs.

Meysam
Thanks again Ivar :) I tried disc cleanup and deleted 15 GBs. Meysam
Meysam Najari
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Posted: 1 decade ago 09.01.2012, 11:34 GMT-5
Hello everyone,

Does anyone know if I can have COMSOL 3.4 and 4.2 on my computer at the same time?

Regards,

Meysam
Hello everyone, Does anyone know if I can have COMSOL 3.4 and 4.2 on my computer at the same time? Regards, Meysam
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 09.01.2012, 15:57 GMT-5
Hi

I would expect so, as COMSOL stores its files in its own separate directory, you need 2 valid licence files, one for each. And 4.2 cannot read 3.4 directly, you need to open it in 3.5a first and then save it once, then you can open the 3.5a file in 4.2. So ideally you need 3 versions ;)

Ask your COMSOL rep for definitive answer, they are there normally to help you for such cases too, no ?

--
Good luck
Ivar
Hi I would expect so, as COMSOL stores its files in its own separate directory, you need 2 valid licence files, one for each. And 4.2 cannot read 3.4 directly, you need to open it in 3.5a first and then save it once, then you can open the 3.5a file in 4.2. So ideally you need 3 versions ;) Ask your COMSOL rep for definitive answer, they are there normally to help you for such cases too, no ? -- Good luck Ivar
Meysam Najari
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Posted: 1 decade ago 11.01.2012, 10:57 GMT-5
Hi Ivar,

Your comments are helpful as always... Thanks :)
Hi Ivar, Your comments are helpful as always... Thanks :)

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