Help with parallel exec on Intel i7

cfdnewbie1 · November 25, 2010, 09:35

Hello to everybody,

I'm a complete newbie with CFD and Star-CCM+.
I'm trying to learn something on this software thru tutorials and examples.

I have the following problem: when I start Star-CCM+ in parallel mode I get the following warning:

Starting local server: starccm+ -server -np 2
Worker Node[2]@XXXX process 692 (MPICH2:nemesis)
Master Node[0]@XXXX process 5460 (MPICH2:nemesis)

STAR-CCM+ Version 4.04.011 (win64/intel10.1)
Worker Node[1]@XXXX process 5404 (MPICH2:nemesis)

Server::start XXXX:51786
Disabling parallel asynchronous communications.
STAR-CCM+ will avoid using non-blocking communication. This may degrade the performance.

My machine is a laptop with a intel-i7 Q720 (4 core - 8 threads), I use Windows 7 64 bit, and MPICH2 ver. 1.3.

My question is: is there a way to configure MPICH2 or Star to use the parallel asynchronous comms? How much does this have an impact on performance?

Thank you very much for your help.

Regards

f-w · November 29, 2010, 15:25

It has a small but measurable effect. There's a checkbox in Tools>Options>Parallel> that you can change.

cfdnewbie1 · November 29, 2010, 15:55

thank you very much! i will do some benchmarks.

fastwave · December 1, 2010, 09:58

What are the disadvantages of using the asynchronous?

cfdnewbie1, I would be interested on the bechmark times. If you can pst them when done that would be appreciated.

fw

cfdnewbie1 · December 23, 2010, 08:27

Here the results of the benchmark done with the bluntbody.sim tutorial.
4 cpus

Enabled
Solution
Accumulated CPU Time over all processes (s) 6007.063
Elapsed Time (s) 1506.699829
Iterations 1500

Disabled
Solution
Accumulated CPU Time over all processes (s) 6178.668
Elapsed Time (s) 1550.230431
Iterations 1500

filippo.aero · December 25, 2010, 05:34

hello, just a simple information: I'm trying to do the same on an i7, but star-ccm replies with "no MPI distribution found", even if I installed mpich2. How did you get it to work? I mean, first installed star, then mpich, etcc

cfdnewbie1 · December 27, 2010, 11:07

You have to start the set the mpich process to start automatically.

try to google
smpd.exe –install
mpiexec.exe –register
you can find all the info!

Hi

November 25, 2010, 09:35	Help with parallel exec on Intel i7	#1
cfdnewbie1 New Member Join Date: Nov 2010 Posts: 5 Rep Power: 16	Hello to everybody, I'm a complete newbie with CFD and Star-CCM+. I'm trying to learn something on this software thru tutorials and examples. I have the following problem: when I start Star-CCM+ in parallel mode I get the following warning: Starting local server: starccm+ -server -np 2 Worker Node[2]@XXXX process 692 (MPICH2:nemesis) Master Node[0]@XXXX process 5460 (MPICH2:nemesis) STAR-CCM+ Version 4.04.011 (win64/intel10.1) Worker Node[1]@XXXX process 5404 (MPICH2:nemesis) Server::start XXXX:51786 Disabling parallel asynchronous communications. STAR-CCM+ will avoid using non-blocking communication. This may degrade the performance. My machine is a laptop with a intel-i7 Q720 (4 core - 8 threads), I use Windows 7 64 bit, and MPICH2 ver. 1.3. My question is: is there a way to configure MPICH2 or Star to use the parallel asynchronous comms? How much does this have an impact on performance? Thank you very much for your help. Regards

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November 29, 2010, 15:25		#2
f-w Senior Member Join Date: Apr 2009 Posts: 159 Rep Power: 17	It has a small but measurable effect. There's a checkbox in Tools>Options>Parallel> that you can change.

November 29, 2010, 15:55		#3
cfdnewbie1 New Member Join Date: Nov 2010 Posts: 5 Rep Power: 16	thank you very much! i will do some benchmarks.

December 1, 2010, 09:58		#4
fastwave New Member Join Date: May 2010 Posts: 14 Rep Power: 16	What are the disadvantages of using the asynchronous? cfdnewbie1, I would be interested on the bechmark times. If you can pst them when done that would be appreciated. fw

December 23, 2010, 08:27		#5
cfdnewbie1 New Member Join Date: Nov 2010 Posts: 5 Rep Power: 16	Here the results of the benchmark done with the bluntbody.sim tutorial. 4 cpus Enabled Solution Accumulated CPU Time over all processes (s) 6007.063 Elapsed Time (s) 1506.699829 Iterations 1500 Disabled Solution Accumulated CPU Time over all processes (s) 6178.668 Elapsed Time (s) 1550.230431 Iterations 1500

December 25, 2010, 05:34		#6
filippo.aero New Member filippo Join Date: Mar 2009 Posts: 10 Rep Power: 17	hello, just a simple information: I'm trying to do the same on an i7, but star-ccm replies with "no MPI distribution found", even if I installed mpich2. How did you get it to work? I mean, first installed star, then mpich, etcc

December 27, 2010, 11:07		#7
cfdnewbie1 New Member Join Date: Nov 2010 Posts: 5 Rep Power: 16	You have to start the set the mpich process to start automatically. try to google smpd.exe –install mpiexec.exe –register you can find all the info! Hi