HPL.dat file contains the configuration parameters. The important parameters are Problem Size, Process Grid, and BlockSize.
Parameter |
Purpose |
|---|---|
Problem Size (N) |
For best results, the problem size must be set large enough to use 80-90% of the available memory. |
Process Grid (P and Q) |
P x Q must match the number of MPI ranks. P and Q must be as close to each other as possible. If the numbers cannot be equal, Q must be larger. |
BlockSize (NB) |
HPL uses the block size for the data distribution and for the computational granularity. Set NB=240 for an optimal performance. |
Set BCASTs=2 |
Increasing-2-ring (2rg) broadcast algorithm gives a better performance than the default broadcast algorithm. |