HPC/Benchmarks/Generation 1 vs 2: Difference between revisions
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== Introduction == | == Introduction == | ||
Earlier this year, we received 200 additional nodes with E5540 processors. | Earlier this year, we received 200 additional nodes with E5540 processors. The processors have 8 cores, and support Hyperthreading, a feature which allows 2 threads per core. This benchmark investigates the benefit of hyperthreading (HT), and suggests optimal values for the ''nodes'' and ''processors per node (ppn)'' parameters in PBS. | ||
== Observations and conclusions == | |||
* 4-core runs give a high numerical throughput in each node type (run=01 to 04) | |||
* gen2 nodes are fine for VASP with nodes=1:ppn=8; gen1 nodes are not (run=22 vs. 21) | |||
* Adding more nodes allows for the fastest run (run=54) or 40% slower and a better charge rate (run=52) | |||
* Running two apps in a single job is mostly not worth the effort of managing them (run=04 vs. 22) | |||
* HT allows for slightly better charge rates, but usually only with non-MPI jobs (or unsynced MPI jobs) (run=15, 25, 40, 55), and runtimes are nearly proportionately longer, making HT largely unattractive. This also holds for the only case tested for HT and napps=1 (run=50). | |||
Revision as of 21:08, March 14, 2010
Introduction
Earlier this year, we received 200 additional nodes with E5540 processors. The processors have 8 cores, and support Hyperthreading, a feature which allows 2 threads per core. This benchmark investigates the benefit of hyperthreading (HT), and suggests optimal values for the nodes and processors per node (ppn) parameters in PBS.
Observations and conclusions
- 4-core runs give a high numerical throughput in each node type (run=01 to 04)
- gen2 nodes are fine for VASP with nodes=1:ppn=8; gen1 nodes are not (run=22 vs. 21)
- Adding more nodes allows for the fastest run (run=54) or 40% slower and a better charge rate (run=52)
- Running two apps in a single job is mostly not worth the effort of managing them (run=04 vs. 22)
- HT allows for slightly better charge rates, but usually only with non-MPI jobs (or unsynced MPI jobs) (run=15, 25, 40, 55), and runtimes are nearly proportionately longer, making HT largely unattractive. This also holds for the only case tested for HT and napps=1 (run=50).