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August 17, 2019

Multi-threading in Psi4 (v 14) Log Out | Topics | Search
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John Keller
Unregistered guest
Posted on Wednesday, May 07, 2014 - 5:56 pm:   

How do we tell Psi4 to use more than one processor?
On the compute node the webmo user can run Psi4 using a "-n 4" switch just fine. The same node is entered in WebMO Pro as a Remote Server with 4 cores (it is a Core i7-930). WebMO runs Gaussian and NWChem jobs with up to 8 processors on this node with no problem. However, if WebMO attempts to run a 4-processor job with Psi4, only 1 processor is used. The run_log entry under Ececuting Command is "/usr/local/psi4/bin/psi4 -p 899 input.inp output.out" that is, no "-n 4" entry. Also, the output.out file refers to 1 thread only.
John Keller
Unregistered guest
Posted on Thursday, May 08, 2014 - 1:10 am:   

The 3rd sentence of the above post should read in part "...as a Remote Server with 8 cores..." That is, 4 physical cores running 2 threads per core.
JR Schmidt
Moderator
Username: Schmidt

Post Number: 396
Registered: 11-2006
Posted on Thursday, May 08, 2014 - 11:06 am:   

John,

The PSI4 interface was written by the PSI4 team, and it appears they did not initially include support for parallel jobs.

This should be easy to add. Try changing the corresponding line in run_psi.cgi to:

my $exec_command = "$psiBase/bin/psi4 -n $nproc -p $jobNumber input.inp output.out";
John Keller
Unregistered guest
Posted on Friday, May 16, 2014 - 4:20 am:   

JR - You'd think that would work..but it doesn't: I get the same entry under Executing Command, and the output.out file is consistent with a single thread being used. BTW, after modifying run_psi.cgi as recommended, I restarted httpd to make sure the new script was seen by the OS.

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