Maximum number of threads for Prime95

treesong · 2012-05-31, 14:48

I am trying to test a 64 core system. I launched the 64 bit Prime95, of version 27.7, the latest. Prime95 crashes quickly. In the prime.txt file, located in the same folder of prime95.exe, I see only w0 - w49, so I guess only 49 worker threads are up. But from the Prime95 wiki, it says for 64bit, the maximum worker threads are 64.
http://en.wikipedia.org/wiki/Prime95

What can I do to make it work?

Thanks!

firejuggler · 2012-05-31, 15:03

Test: worker windows and adjust?
(just a nitpick 0-49 is 50, not 49)

Dubslow · 2012-05-31, 18:31

I can't say off the top of my head, but I would say take a look through readme.txt, undoc.txt, and maybe even whatsnew.txt and do a Ctrl+F on some relevant terms.

petrw1 · 2012-05-31, 19:10

I have 64 bit V26.2.1 and according to my undoc.txt the limit in that version is 32 workers.

Worst case you could have 32 workers with 2 cores per worker and still probably get 95+% effectiveness.

However post #2 in the Prime95 V27.7 thread implies it supports more than 36.
http://www.mersenneforum.org/showthread.php?t=16779

Also read posts 31+.

treesong · 2012-05-31, 19:57

Quote:

Originally Posted by firejuggler

Test: worker windows and adjust?
(just a nitpick 0-49 is 50, not 49)

Sorry, my bad, the worker thread in the prime.txt file started from w1, not w0, and that is why I said there were only 49 of them.

treesong · 2012-05-31, 20:04

Quote:

Originally Posted by petrw1

I have 64 bit V26.2.1 and according to my undoc.txt the limit in that version is 32 workers.

Worst case you could have 32 workers with 2 cores per worker and still probably get 95+% effectiveness.

However post #2 in the Prime95 V27.7 thread implies it supports more than 36.
http://www.mersenneforum.org/showthread.php?t=16779

Also read posts 31+.

-----------------------------------------------------------------------------------------
I tried version 27 on a 48 core system, and I got 100% of stress load of each every of the cores, then I tried to start 49, 50 or 64 threads, then Prime95 would crash. OK, I will try to launch 2 instances of prime95, with 32 threads each.

treesong · 2012-05-31, 20:13

Quote:

Originally Posted by petrw1

I have 64 bit V26.2.1 and according to my undoc.txt the limit in that version is 32 workers.

Worst case you could have 32 workers with 2 cores per worker and still probably get 95+% effectiveness.

However post #2 in the Prime95 V27.7 thread implies it supports more than 36.
http://www.mersenneforum.org/showthread.php?t=16779

Also read posts 31+.

-----------------------------------------------------------------------------------------

Forgot to say earlier, thank you for all your input!

Attached please find the screen shot of the 48 core system.

treesong · 2012-05-31, 20:17

Quote:

Originally Posted by petrw1

I have 64 bit V26.2.1 and according to my undoc.txt the limit in that version is 32 workers.

Worst case you could have 32 workers with 2 cores per worker and still probably get 95+% effectiveness.

However post #2 in the Prime95 V27.7 thread implies it supports more than 36.
http://www.mersenneforum.org/showthread.php?t=16779

Also read posts 31+.

----------------------------------------------------------------------------------------- I tried running two instances of prime95, with 32 worker threads each, and I got 98% of the stress load. Thank you so much!!!

Prime95 · 2012-05-31, 22:40

Quote:

Originally Posted by treesong

What can I do to make it work?

Ship your 64-core system to me and I'll do some debugging. I should have the system back to you in a year or two :)

kracker · 2012-05-31, 22:59

Quote:

Originally Posted by Prime95

Ship your 64-core system to me and I'll do some debugging. I should have the system back to you in a year or two :)

ixfd64 · 2012-06-16, 01:15

A scrollable MDI would be quite useful in this case: http://www.mersenneforum.org/showthread.php?t=16083

2012-05-31, 14:48	#1
treesong May 2012 6₁₆ Posts	Maximum number of threads for Prime95 I am trying to test a 64 core system. I launched the 64 bit Prime95, of version 27.7, the latest. Prime95 crashes quickly. In the prime.txt file, located in the same folder of prime95.exe, I see only w0 - w49, so I guess only 49 worker threads are up. But from the Prime95 wiki, it says for 64bit, the maximum worker threads are 64. http://en.wikipedia.org/wiki/Prime95 What can I do to make it work? Thanks! Attached Thumbnails

2012-05-31, 19:10	#4
petrw1 1976 Toyota Corona years forever! "Wayne" Nov 2006 Saskatchewan, Canada 5322₁₀ Posts	I have 64 bit V26.2.1 and according to my undoc.txt the limit in that version is 32 workers. Worst case you could have 32 workers with 2 cores per worker and still probably get 95+% effectiveness. However post #2 in the Prime95 V27.7 thread implies it supports more than 36. http://www.mersenneforum.org/showthread.php?t=16779 Also read posts 31+. Last fiddled with by petrw1 on 2012-05-31 at 19:15

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2012-05-31, 15:03	#2
firejuggler "Vincent" Apr 2010 Over the rainbow 5·11·53 Posts	Test: worker windows and adjust? (just a nitpick 0-49 is 50, not 49)

2012-05-31, 18:31	#3
Dubslow Basketry That Evening! "Bunslow the Bold" Jun 2011 40<A<43 -89<O<-88 3×29×83 Posts	I can't say off the top of my head, but I would say take a look through readme.txt, undoc.txt, and maybe even whatsnew.txt and do a Ctrl+F on some relevant terms.

2012-06-16, 01:15	#11
ixfd64 Bemusing Prompter "Danny" Dec 2002 California 9C7₁₆ Posts	A scrollable MDI would be quite useful in this case: http://www.mersenneforum.org/showthread.php?t=16083