Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.
Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
No speedup when using distributed memory cluster
Posted 23 May 2012 09:54 GMT-04:00 Installation & License Management, Studies & Solvers Version 4.2a 1 Reply
I understand that speedup is highly model dependent. Per the suggestions of previous discussion threads, I have tried numerous different models with different physics (both linear and non-linear problems). Also, I have tried large memory models and small memory models (also per previous thread recommendations). Below are my results using the COMSOL Model Library Example "Micromixer Cluster Version":
Micromixer_cluster.mph (mesh as given):
1 node; 1 proc.: Run time = 123 sec
1 node; 12 proc.: Run time = 38 sec
4 nodes; 12 ppn: Run time = 99 sec
8 nodes; 12 ppn: Run time = 223 sec
I see speedup when I go from 1 proc. to 12 proc. running on 1 node (shared memory), but I don't see speedup, in fact I see slowdown, when I try to distribute the job across multiple nodes (distributed memory). The step-by-step instructions said to try refining the mesh for better speedup (this was also COMSOL support's recommendation). Here are the results for 2 different refined meshes:
Micromixer_cluster.mph (refined mesh):
1 node; 1 proc.: Run time = 566 sec
1 node; 12 proc.: Run time = 130 sec
4 nodes; 12 ppn: Run time = 259 sec
8 nodes; 12 ppn: Run time = 501 sec
Micromixer_cluster.mph (super-refined mesh):
1 node; 1 proc.: Run time = 1169 sec
1 node; 12 proc.: Run time = 414 sec
4 nodes; 12 ppn: Run time = 614 sec
8 nodes; 12 ppn: Run time = 896 sec
Still no speedup. Only slowdown.
Has anyone seen any speedup on this COMSOL Model Library example? If so, I'd be interested in your results.
One thing that I am doing that is different than the COMSOL recommendation is submitting jobs through the command line rather than through the Desktop. Does anyone know why COMSOL recommends submitting batch cluster jobs through the Desktop and not through the command line? Could this be my issue?
Any help would be appreciated.
Hello Josh Thomas
Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.
If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.