[TRNSYS-users] Quicker processing speeds?

Fri Nov 10 12:49:17 PST 2006

Quicker processing speeds?Dear Rémi and TRNSYS users,

We recently did some experimenting with a dual-core processor. Our aim was actually to find out if the hard disk writing of a computer could be saturated by large TRNSYS outputs and thus become a bottle-neck in simulations with big output files (and it seems like not easily with standard modern computers).

But...

To benefit from a dual core processor a program must be multi-tasking, i.e. it must create multiple threads for the operating system (OS) which the OS can then run in parallel. TRNSYS does not create multiple threads, so if you are running only one simulation on a dual core processor, it will run just as fast as if you would run it on a single core. However, you can run two TRNSYS simulations simultaneously, and the OS will then run each simulation on its own core. This means that you can run e.g. two parametric studies (or divide one into two) at the same time and thus halve the needed time.  BUT TAKE CARE: you must run two decks from separate directories and see that also the output files end up in different directories!!! (or change the names) Otherwise the simulations will write to same files, the output data of the first started will be replaced by the later started. 

I have no knowledge of how much you can benefit of dual core processors when calling other programs from TRNSYS or with plugins. But based on what is stated above, I'd say that you will benefit only, if the other programs can do something useful while TRNSYS is solving. If TRNSYS solver pauses for feedback from the other program and vice versa for each iteration or time-step, you will probably have no notable perfomance boost. But, for example, if the other program does data processing or writing to the hard disk each time step after it has given feedback to TRNSYS then you might benefit, as this will be done by the other core and TRNSYS can continue a bit earlier. You have to try and see... 

Also, I don't know what happens with communication between TRNSYS and the other programs if there are several instances running... I have only tried with TRNSYS without external connections.

I'd also be very interested to hear if other people have more experience on this.

What comes to RAM, you should check how much you are using with current simulations. You can do that with the windows performance monitor by checking how much RAM is used and how much it changes when you start a simulation. Additional RAM will only help if the OS is writing to the paging file (virtual memory on hard disk) while you are running the simulation. 1GB for the computer should be more than enough, but it depends of course on what other programs and system processes are running simultaneously... TRNSYS does not eat memory as e.g. FEM/CFD does.

What comes to processor speeds, the sim time should be somewhat directly proportional to processor speed, so faster is better. That is, if there are no other bottle-necks on the motherboard (bus speeds, cache etc.). Usually in good quality commercial computers (or built by experts) there should be no problems with processor not being optimized with motherboard. (but changing a processor to your existing motherboard is another thing...)

Hope that helps at least as a starting point...

Cheers

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Janne Paavilainen 
MSc, PhD student
Researcher in Energy and Environmental engineering
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Solar Energy Research Center SERC
Dalarna University College
SE-781 88 Borlänge
Sweden
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fax +46 (0)23 778701
e-mail: jip at du.se
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  ----- Original Message ----- 
  From: Charron, Rémi 
  To: trnsys-users at engr.wisc.edu 
  Sent: Friday, November 10, 2006 6:43 PM
  Subject: [TRNSYS-users] Quicker processing speeds?

  Hello, 
  I am currently running TRNSYS with using a computer with a 3.2 GHz prcoessor with 512 MB of RAM.  It takes approximately 100 seconds to run a simulation.  This is a reasonable amount of time, except that I am running TRNSYS with an optimisation program and am requiring to perform thousands of TRNSYS simulations per run.  I am thinking of getting a quicker computer or workstation to help speed TRNSYS up.  Has anyone had experience running TRNSYS using duel core processors or other high performance computers or workstations?  If so, what have been your experiences?  Can the computation time be significantly reduced with the use of a more powerful computer?

  Thanks, 

  Rémi Charron 
  Research Officer 
  Photovoltaic and Hybrid System Program 
  CANMET Energy Technology Centre 
  1615 Lionel-Boulet Blvd, P.O. Box 4800, J3X 1S6 
  Varennes, Quebec 
  Tel: (450) 652-7948, Fax: (450) 652-5177 
  http://cetc-varennes.nrcan.gc.ca 

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