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2020-04-01, 17:22   #496
Prime95
P90 years forever!

Aug 2002
Yeehaw, FL

675410 Posts

Quote:
 Originally Posted by jdhedden I'm trying to run mprime on a AMD Ryzen 7 3800X 8-Core Processor. I've run with different numbers of threads with the following approximate throughputs: 1 thread : 20ms/iter 2 threads: 31ms/iter 4 threads: 60ms/iter 7 threads: 100ms/iter.
We need to work on terminology first. Since your timings are getting worse, I think you are timing 1,2,4,7 workers (that is testing 1,2,4,7 different exponents). You can also time one worker using multiple threads. In this case, timings will decrease.

In either scenario, at some point your timings will likely be constrained by your RAM's bandwidth.

2020-04-01, 20:58   #497
jdhedden

Mar 2020

2 Posts

Quote:
 Originally Posted by Prime95 We need to work on terminology first. Since your timings are getting worse, I think you are timing 1,2,4,7 workers (that is testing 1,2,4,7 different exponents). You can also time one worker using multiple threads. In this case, timings will decrease. In either scenario, at some point your timings will likely be constrained by your RAM's bandwidth.
Yes, I agree that my terminology may be off. I have 2 exponents. I'm configured to run 2 workers. When running, the system reports 200% cpu usage, indicating 2 threads are being used. (I'm on a Linux machine (Debian OS) with an AMD Ryzen 7 which has 8 cores = 16 cpus (threads).)

When I was using 4 workers/exports, it said 400% cpu - again, 4 threads used. However, ms/iter also went up by 2 which indicates that total "throughput" remained constant even though more cpus were involved.

I've tried setting cpu frequencies:
Code:
for xx in 8 9 10 11 12 13 14 15; do
sudo cpufreq-set --freq 3.90GHz --cpu \$xx
done
In conjunction with cpu affinities in local.txt:
Code:
[Worker #1]
Affinity=8-9,10-11
[Worker #2]
Affinity=12-13,14-15
But this had no affect on reducing the ms/iter.

So it may be that I'm not configured make the most of my computer's resources. Suggestions?

2020-04-01, 22:52   #498
Prime95
P90 years forever!

Aug 2002
Yeehaw, FL

2·11·307 Posts

Quote:
 Originally Posted by jdhedden Suggestions?
Ryzen owners mmay be able to offer better advice. I would guess you will get maximum throughput with 1 worker using 8 threads.

The benchmark menu choice will tell you which configuration gives he best throughput. Assuming you are doing first time tests, benchmark the 5120K FFT size, 8 cores, 1.2.4.8 workers.

Afterwards use the Worker Windows menu choice to create the proper number of workers using the proper number of threads. Direct editing prime.txt and local.txt is not recommended for newcomers.

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