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Old 2015-10-11, 05:16   #1
Karl M Johnson
 
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Default Test a specific exponent with Prime95

Good day.

It's been a while since I've used Prime95, truth be told, that was before CUDALucas/mfaktc.
Back then I recall there was a way to force a worker to use all CPU resources in a LL test. Is that functionality still there?

I have found the strings below using Google and mersenneforum's internal search, but two of them were not listed in undoc (deprecated?):
Code:
Affinity=0
WorkerThreads=n
ThreadsPerTest=n
None of this helped, perhaps AdvancedTest wasn't the right way?

So, is there still a way to perform a LL test on a specific exponent with Prime95 utilising all CPU resources?
I'm well aware of the diminishing returns of such an approach, and how superior running a LL test per physical core is.
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Old 2015-10-11, 05:57   #2
ATH
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You just need set WorkerThreads=1 and ThreadsPerTest to the number of physical cores you have (not hyper threaded cores).

So most likely ThreadsPerTest=4 unless you have an older or newer/expensive computer.
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Old 2015-10-11, 06:54   #3
Karl M Johnson
 
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I've already did that, but for the purpose of the experiment, did it again.
Set
Code:
WorkerThreads=1
ThreadsPerTest=8
in prime.txt(8C16T), launched a LL primality test through Prime95 GUI (Advanced -> Test).
Did not work, CPU utilization was at 6.25%(1/16th).
Any ideas?

Last fiddled with by Karl M Johnson on 2015-10-11 at 07:01
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Old 2015-10-11, 07:29   #4
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If you are running Prime95 with a GUI (the Windows version for instance) you can set the number of workers and threads trough the menus.Menu "Test", "Worker windows...". Then you can set the number of worker windows and the number of CPUs to use. Setting the values in the configuration files should work as well but you have to stop Prime95 before doing a change : the values are read by the program at the start of a run.

Jacob

Last fiddled with by S485122 on 2015-10-11 at 07:56 Reason: à instead of )
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Old 2015-10-11, 07:45   #5
Karl M Johnson
 
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Magnificent, everything works now!
Those strings should have been placed into local.txt, not prime.txt
Thank you for your assistance!
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Old 2015-10-11, 17:26   #6
Madpoo
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Quote:
Originally Posted by Karl M Johnson View Post
I've already did that, but for the purpose of the experiment, did it again.
Set
Code:
WorkerThreads=1
ThreadsPerTest=8
in prime.txt(8C16T), launched a LL primality test through Prime95 GUI (Advanced -> Test).
Did not work, CPU utilization was at 6.25%(1/16th).
Any ideas?
Remember, do *not* count hyperthreaded cores in your total. If I were guessing, you probably have a 4-core desktop, and only 8 if you count the hyperthreaded ones, which you shouldn't for purposes of Prime95.

But maybe you really do have an 8 *physical* core system, in which case you're fine.
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Old 2015-10-11, 19:49   #7
ATH
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Disable hyper threading in your BIOS if you can, because it is not really helping.

If you keep hyper threading on and use ThreadsPerTest=4 (assuming 4 physical cores and 4 HT), then the task manager will show only 47-50% cpu use, but it will actually use the entire cpu.
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Old 2015-10-12, 03:30   #8
LaurV
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Quote:
Originally Posted by Karl M Johnson View Post
8C16T
Quote:
Originally Posted by Madpoo View Post
If I were guessing reading
Fixed it for you...
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Old 2015-10-12, 05:36   #9
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Quote:
Originally Posted by LaurV View Post
Fixed it for you...


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Old 2015-10-12, 13:20   #10
Karl M Johnson
 
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50% CPU utilisation was observed, but since I've read about it in another thread, I wasn't surprised (plus the core temps on the graphs spiked the way they do when all resources are utilised).
I've set affinity most efficiently, even with HT on, and the timings reflected that.
LL DC was a great success and a match, nearly as fast as GTX Titan performs it.
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Old 2015-10-12, 15:10   #11
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Quote:
Originally Posted by LaurV View Post
Fixed it for you...
Yeah, I saw that (later, after I replied of course), but then I thought maybe the OP made an incorrect assumption. I guess not.
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