GEN21 MT CPU, I am wondering if my 10980XE do better with two units and 9 cores, or one unit and 18 cores?
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My lucky numbers are 121*2^4553899-1 and 3756801695685*2^666669±1
My movie https://vimeo.com/manage/videos/502242

I am trying, and failing, to recall if MT still works on GFN-21.

If it is similar to other ~16 MB tasks - run 2 each of 9 threads.
It should be totally OK to run 2 x 8 thread tasks and keep a couple of threads for yourself.

I am going to amend previous - I don't know.
What happens with the task on the GPU?
Does that use CPU cache?

This does not seem to work

Try this one:

<app_config>
<app_version>
<app_name>genefer</app_name>
<cmdline>-nt 4</cmdline>
<plan_class>cpuGFN21</plan_class>
<avg_ncpus>4</avg_ncpus>
</app_version>
</app_config>

That is one I've successfully used in the past. Change the 4's to 18's and you should be good to go.
You may still get an error like the one you've mentioned if you've never run GFN21 on that system before. But that's okay and you can ignore it.

Figured it out. Had to go before the GPU ones I had in the list, now it worked. Still downloaded 18 the first time, but says running 18 CPU, so I aborted the other 17 and it should hopefully only grab one at a time afterward.
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My lucky numbers are 121*2^4553899-1 and 3756801695685*2^666669±1
My movie https://vimeo.com/manage/videos/502242

Running 18 cores, and it is running along well. I finish them faster than the DYFL ones on my GPU. This rig currently is only doing crunching (yes, I know such a high end machine just for crunching, but circumstances...). I am amazed at the speed of this machine and the work it puts out.
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My lucky numbers are 121*2^4553899-1 and 3756801695685*2^666669±1
My movie https://vimeo.com/manage/videos/502242

Reusing a thread instead of creating a new one.
Curiosity has me wondering why more GFN cannot be run CPU MT? If we have one that can do it, and it runs really well, what makes the others not as desirable to do so? I'd love to be able to push out some of the larger GFN quicker on CPU.
____________
My lucky numbers are 121*2^4553899-1 and 3756801695685*2^666669±1
My movie https://vimeo.com/manage/videos/502242

Reusing a thread instead of creating a new one.
Curiosity has me wondering why more GFN cannot be run CPU MT? If we have one that can do it, and it runs really well, what makes the others not as desirable to do so? I'd love to be able to push out some of the larger GFN quicker on CPU.

https://www.primegrid.com/forum_thread.php?id=9821&nowrap=true#153138

Yves Gallot said:

Multithreading is not needed for GFN-17. The data size is 2 MB. On Intel processors the L3 cache size is #cores * 2MB and on AMD CPU it is #cores * 2MB or * 4MB or more.

I guess it's meant to utilize as much cache available on your CPU to improve your throughput.