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 2015-10-11, 05:16 #1 Karl M Johnson     Mar 2010 41110 Posts 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.
 2015-10-11, 05:57 #2 ATH Einyen     Dec 2003 Denmark 2×3×7×71 Posts 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.
 2015-10-11, 06:54 #3 Karl M Johnson     Mar 2010 3×137 Posts 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
 2015-10-11, 07:29 #4 S485122     Sep 2006 Brussels, Belgium 1,597 Posts 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 )
 2015-10-11, 07:45 #5 Karl M Johnson     Mar 2010 3×137 Posts Magnificent, everything works now! Those strings should have been placed into local.txt, not prime.txt Thank you for your assistance!
2015-10-11, 17:26   #6
Serpentine Vermin Jar

Jul 2014

63158 Posts

Quote:
 Originally Posted by Karl M Johnson 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.

 2015-10-11, 19:49 #7 ATH Einyen     Dec 2003 Denmark 2×3×7×71 Posts 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.
2015-10-12, 03:30   #8
LaurV
Romulan Interpreter

Jun 2011
Thailand

22·7·11·29 Posts

Quote:
 Originally Posted by Karl M Johnson 8C16T
Quote:
Fixed it for you...

2015-10-12, 05:36   #9
Dubslow

"Bunslow the Bold"
Jun 2011
40<A<43 -89<O<-88

3×2,399 Posts

Quote:
 Originally Posted by LaurV Fixed it for you...

 2015-10-12, 13:20 #10 Karl M Johnson     Mar 2010 3×137 Posts 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.
2015-10-12, 15:10   #11
Serpentine Vermin Jar

Jul 2014

29×113 Posts

Quote:
 Originally Posted by LaurV 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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