mprime is significantly slowing down other programs

[Chai T Rex]

The problem I'm having is that, for whatever reason, mprime is significantly slowing down the other programs that I'm running. I frequently have to turn off mprime and then I'll forget to turn it back on when I'm done using the computer.

How can I limit mprime so that this doesn't happen? Is there some way to, for example, limit the number of CPU cores that mprime is using? Is there some other way to stop mprime from interfering with the performance of other programs?

I'm using mprime (Mersenne number primality test program version 30.8) on Ubuntu 22.04 with a Ryzen 5900X.

[kriesel]

Originally Posted by Chai T Rex

The problem I'm having is that, for whatever reason, mprime is significantly slowing down the other programs that I'm running. I frequently have to turn off mprime and then I'll forget to turn it back on when I'm done using the computer.

How can I limit mprime so that this doesn't happen? Is there some way to, for example, limit the number of CPU cores that mprime is using? Is there some other way to stop mprime from interfering with the performance of other programs?

I'm using mprime (Mersenne number primality test program version 30.8) on Ubuntu 22.04 with a Ryzen 5900X.

Yes. What does top show? Normally mprime /prime95 runs at low priority, but by default assigns all cores to worker(s). There are ways to reduce the number of cores, number of workers, etc. It comes with fairly good documentation included. Reading its readme.txt and undoc.txt is likely to be informative and helpful.

Welcome to the forum. You may also find some of the reference info collection useful, now or later. Good luck.

[storm5510]

Originally Posted by kriesel

Yes. What does top show? Normally mprime /prime95 runs at low priority, but by default assigns all cores to worker(s). There are ways to reduce the number of cores, number of workers, etc. It comes with fairly good documentation included. Reading its readme.txt and undoc.txt is likely to be informative and helpful.

Welcome to the forum. You may also find some of the reference info collection useful, now or later. Good luck.

When I first set up this i7 system back in 2018, Mark Rose suggested the following be placed in prime.txt

WorkerThreads=1
CoresPerTest=4

I have kept it there. Prime95 can be aggressive about using resources despite running at a low priority. I have mprime on my Ubuntu box. I applied the above to it also.

[kriesel]

The 5900x has 12 cores and supports 24 threads. https://www.pcmag.com/reviews/amd-ryzen-9-5900x

[storm5510]

Originally Posted by kriesel

The 5900x has 12 cores and supports 24 threads. https://www.pcmag.com/reviews/amd-ryzen-9-5900x

In this situation, I would not use any more than 8 cores per test and stick with one worker thread. Something else I do, actually don't do, is run any CPU intensive processes in tandem with Prime95. I run it as a sole process. In the past, I have tried running other things with it, but it did not work very well. Hard resets would occur. Low impact things, like Excel do not cause problems.

[Mark Rose]

Originally Posted by storm5510

When I first set up this i7 system back in 2018, Mark Rose suggested the following be placed in prime.txt

WorkerThreads=1
CoresPerTest=4

I have kept it there. Prime95 can be aggressive about using resources despite running at a low priority. I have mprime on my Ubuntu box. I applied the above to it also.

That's applicable to a machine with 4 cores on a single chiplet.

For a 5900X, which has two chiplets with six cores each, the best configuration for mprime performance would be

WorkerThreads=2
CoresPerTest=6

[Mark Rose]

Originally Posted by Chai T Rex

The problem I'm having is that, for whatever reason, mprime is significantly slowing down the other programs that I'm running. I frequently have to turn off mprime and then I'll forget to turn it back on when I'm done using the computer.

How can I limit mprime so that this doesn't happen? Is there some way to, for example, limit the number of CPU cores that mprime is using? Is there some other way to stop mprime from interfering with the performance of other programs?

I'm using mprime (Mersenne number primality test program version 30.8) on Ubuntu 22.04 with a Ryzen 5900X.

What you're likely running into is memory bandwidth saturation. Each memory channel will roughly support 2 cores. Additional cores may give a little more performance, but they are limited by memory bandwidth.

I'd try the following in local.txt (or prime.txt in 30.11 or later):

WorkerThreads=1
CoresPerTest=6

and lower 6 until you get acceptable performance.

You can also play with the PauseWhileRunning= option in prime.txt.

30.12 adds support for changing CoresPerTest on a time schedule. 30.12 is still undergoing testing.