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Old 2021-07-24, 17:47   #38
drkirkby
 
"David Kirkby"
Jan 2021
Althorne, Essex, UK

3·149 Posts
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(kriesel: Caution, next post indicates there was an undisclosed error affecting this post.)


I tried what you said, but performance was not that great. Then I tried running one process with 2 workers, with Affinity like you said, and benchmarking another process. The benchmarking was tried with 24-26 cores and 2-4 workers.

Code:
[Worker #1 Jul 24 16:57] Timing 5760K FFT, 26 cores, 4 workers.  Average times:  8.29,  7.12,  6.24,  5.37 ms.  Total throughput: 607.58 iter/sec.
Since 4 does not divide 26, clearly there must be an unequal number of cores running on each worker.

The 607.58 iter/sec is almost double the throughput one obtains running 4 workers on each of two processes, where the processes are not constrained in any way. Here are the results from running two benchmarks, where nothing is constrained.

Code:
[Worker #1 Jul 24 18:14] Benchmarking multiple workers to measure the impact of memory bandwidth
[Worker #1 Jul 24 18:15] Timing 5760K FFT, 26 cores, 4 workers.  Average times: 13.27, 11.03, 13.31, 11.08 ms.  Total throughput: 331.31 iter/sec.
and
Code:
[Worker #1 Jul 24 18:15] Timing 5760K FFT, 26 cores, 4 workers.  Average times: 12.80, 11.30, 12.78, 11.42 ms.  Total throughput: 332.36 iter/sec.
Total throughput is a dismal 331.31+332.36=663.67 iter/sec.

One does better running one process
Code:
[Worker #1 Jul 24 18:22] Benchmarking multiple workers to measure the impact of memory bandwidth
[Worker #1 Jul 24 18:22] Timing 5760K FFT, 52 cores, 4 workers.  Average times:  3.85,  3.84,  3.86,  3.86 ms.  Total throughput: 1038.20 iter/sec.
I suppose the next thing to try is to run two processes, each with 4 workers. I guess 2x6+2x7=26 would be a reasonable It would be nice to think I could get a total throughput of 2*607.58 = 1215.16 iter/sec, but somehow I doubt that will happen.

Last fiddled with by kriesel on 2021-07-25 at 00:05 Reason: error indicated in next post
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