CODEWITHSUNDEEP
mpi
user1612078
user1612078

Reputation: 585

How to calculate the speedup of MPI application?

I wish to calculate the speedup of my MPI application against the number of parallel processes/nodes.

Application mostly performs huge matrices computation in parallel. I can measure an elapsed time using MPI_Wtime(), something like this..

double start = MPI_Wtime();  
....
double end = MPI_Wtime();
double elapsed = end - start;

But how can I achieve this against the degree of parallelization ?

Upvotes: 0

Views: 3061

Answers (1)

Adam
Adam

Reputation: 17329

The usual definition of speedup is time on 1 process divided by time on p processes.

If you wish to present the performance of your code, it's good to pick a range of p from 1 to the highest amount you have access to run and plot the results on a speedup vs. p plot.

Note that strictly speaking, speedup should compare the time on p processes vs the best possible sequential code, not just running your parallel code sequentially. This seems like a moot point, but in some areas the parallel codes are pretty awful in the sequential case. In the sparse matrix world, for example, you can find a parallel code 10-50x slower than the top sequential code.

Upvotes: 3

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