MPI slides - bandwidth measurement#20
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CharlesVanHees wants to merge 2 commits into
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I did more explicit the size of the data to make the distinction clear between gather where $x_i$ has size n/p and reduce where it has size n
To make the code coherent with the comment in the slide (about the accuracy of the bandwidth measurement), I think we should measure on sender's side?
blegat
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May 27, 2025
| double tic = MPI_Wtime(); | ||
| MPI_Send(buf, size, MPI_CHAR, procid + 1, tag++, comm); | ||
| double toc = MPI_Wtime(); | ||
| printf("[%d] I have send %d B in %f sec\n", procid, size, (toc-tic)); |
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| printf("[%d] I have send %d B in %f sec\n", procid, size, (toc-tic)); | |
| printf("[%d] I have sent %d B in %f sec\n", procid, size, (toc-tic)); |
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Hello,
For the bandwidth measurement, I think there is a coherence problem between the code and the comment. Or I have not understood perfectly the comment otherwise? I have modified the code, but we could also modify the comment.
I profit of this commit to make the size of the data more explicit in the collectives (to distinguish better$x_i$ of the gather and reduce collectives).
Kind regards,
Charles