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Mplus Discussion > Structural Equation Modeling >
 Maria Caridad García-Cepero posted on Tuesday, May 29, 2007 - 11:39 am
I just bought a new computer (AMD Athlon 64 X2 4000+)
I am not sure how to take advantage of the Multi-processing speed gains. Do I have to do a special set up for MPLUS or MPLUS 4.21 automatically does?
I have notice that when I run my models (for instance I am running some MIMIC models with zero-inflated poison endogenous indicators in a sample of 4000 subjects) that I am only using one of the processors but never two. Is it normal?
 Thuy Nguyen posted on Tuesday, May 29, 2007 - 11:59 am
Yes, Mplus only uses one processor by default. You need to specify the number of processors Mplus should use with the PROCESSORS option in the ANALYSIS command.

For example:

 Matthew Cole posted on Friday, July 13, 2007 - 7:23 pm

This really speeds up the analysis, particularly when running the mixture analyses with random starts.
 Spencer James posted on Friday, February 17, 2012 - 7:31 am
Is there a limit to how many processors Mplus can/will use?
 Linda K. Muthen posted on Friday, February 17, 2012 - 1:43 pm
 Anonymous posted on Thursday, July 05, 2012 - 10:55 am
I have a quad-processor desktop with 4MB, and would have assumed that the maximum number of processors I could run would be 4. However I tried 8 and this seemed to work. Should this be?
 Linda K. Muthen posted on Friday, July 06, 2012 - 11:19 am
We have no way of knowing how many processors a computer has. If you say you have more than you do, this could cause Mplus to run inefficiently. You should state the number of processors correctly.
 Robert Nichols posted on Friday, April 01, 2016 - 3:26 pm
When using the PROCESSORS option should I specify the number of cores or the number of logical processors? I have 4 cores and 8 logical processors.
 Thuy Nguyen posted on Saturday, April 02, 2016 - 1:29 pm
You should specify the number of logical processors that you want to use. So on a quad-core computer with hyperthreading, you can specify PROCESSORS=8.
 Peter posted on Sunday, January 29, 2017 - 8:28 am
Dear Drs. Methuen,

1) Could you update (Jan 30, 2017) specific M-Plus commands which run faster on multiple cores. i.e.,


2) Have all of these listed M-Plus commands in 1) above been parallelized in your code so that they can take advantage of multiple cores?

Would you please comment on the following:

3) In benchmarking timing tests within Stata and Geekbench, we found faster parallel processing times when only hardware cores were specified to be used; that is, while virtual cores were left free.

Our best impression for this difference, while watching Mac OSX and Windows 8 allocate the work load among multiple processors (on the same dual boot machine),
is that it is best to leave all virtual cores free for operating system calls and other "housekeeping" chores that are required while floating point, matrix algebra math computation is ongoing on the hardware cores.

Have tests WITHIN M PLUS on your multiple core machine, confirmed or refuted point 3) above?

Thank you,

 Tihomir Asparouhov posted on Monday, January 30, 2017 - 9:23 am
1) All the up to date information on that is in the Mplus users guide page 648-650

2) yes

3) no - however there is such a great variety of processor and OS that I wouldn't generalize too much here. On Intel CPUs and Windows OS using virtual cores is faster.
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