Beforedoing any MPI programming, make sure to load the MPI module on Unix:
$ module load mpi/openmpi-x86_64Or, if you are using Mac, just:
$ brew install open-mpiYou can make the module with <dir> $make
$ makeon
makeyou will have an executable compiled with debug and compilation warnings turned on.-lmstands for<math.h>library inclusion.
$ make cleanthis will remove the executable as well as all of the generated
.txtfiles.
$ mpiexec -n <P> genprimes <N>Where <P> stands for the number of MPI processes and <N> is the upper bound on the prime range.
| #P vs N | 1k | 10k | 100k | 1M | 10M | 1B |
|---|---|---|---|---|---|---|
| 1 | 0.249s | 0.25s | 0.273s | 0.701s | 10.946s | Absolutely huge |
| 2 | 0.265s | 0.265s | 0.273s | 0.457s | 4.485s | Ridiculously big |
| 5 | 0.298s | 0.296s | 0.301s | 0.380s | 1.645s | Big |
| 10 | 0.370s | 0.372s | 0.377s | 0.417s | 1.023s | 289.819s |
| 100 | 3.721s | 3.766s | 3.703s | 3.678s | 4.072s | 42.161s |
the numbers are averaged over 10 consecutive runs of the program.
Note: 100 processes perform worse due to the fact that for
N < 1Bthe communication between the processes is more expensive than the computation.
These measurements were taken on a Four AMD Opteron 6272 (2.1 GHz) (64 cores), with 256GB RAM and Cent OS 7 in a virtual environment with 4GB RAM available and 1 CPU available.
Copyright 2020 Andrii Lunin.
Open source code available under MIT Licence.