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LAMMPS: Difference between revisions
→CPU efficiency
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== CPU efficiency == | == CPU efficiency == | ||
LAMMPS uses the domain decomposition to split the work among the available processors by assigning a small subset of simulation box to each available processor. During the computation of the interactions between particles, a communication between the processors is required. For a given number of particles, more processors used, more subsets of the simulation box are used. Therefore, the communication time will increase | LAMMPS uses the domain decomposition to split the work among the available processors by assigning a small subset of simulation box to each available processor. During the computation of the interactions between particles, a communication between the processors is required. For a given number of particles, more processors used, more subsets of the simulation box are used. Therefore, the communication time will increase leading to a low CPU efficiency. | ||
Before running extensive simulations for a given problem size or a size of the simulation box, it is recommended to run some tests to see how the program scales with increasing the number of cores. The idea is to run short tests using different number of cores in order to determine the suitable number of core that will maximize the efficiency of the simulation. | Before running extensive simulations for a given problem size or a size of the simulation box, it is recommended to run some tests to see how the program scales with increasing the number of cores. The idea is to run short tests using different number of cores in order to determine the suitable number of core that will maximize the efficiency of the simulation. | ||
Section | {| class="wikitable" style="text-align: center; border-width: 2px;width: 100%;" | ||
!Section | |||
Pair | |min time | ||
Neigh | |avg time | ||
Comm | |max time | ||
Output | |%varavg | ||
Modify | |%total | ||
Other | |- | ||
!Pair | |||
|6.6964 | |||
|7.1974 | |||
|7.9599 | |||
|14.8 | |||
|46.45 | |||
|- | |||
!Neigh | |||
|0.94857 | |||
|1.0047 | |||
|1.0788 | |||
|4.3 | |||
|6.48 | |||
|- | |||
!Comm | |||
|6.0595 | |||
|6.8957 | |||
|7.4611 | |||
|17.1 | |||
|44.50 | |||
|- | |||
!Output | |||
|0.01517 | |||
|0.01589 | |||
|0.019863 | |||
|1.0 | |||
|0.10 | |||
|- | |||
!Modify | |||
|0.14023 | |||
|0.14968 | |||
|0.16127 | |||
|1.7 | |||
|0.97 | |||
|- | |||
!Other | |||
| - | |||
| 0.2332 | |||
| - | |||
| - | |||
|1.50 | |||
|- | |||
} | |||
= Related Software = | = Related Software = | ||