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Old 2012-05-31, 14:48   #1
treesong
 
May 2012

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Default 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!
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Old 2012-05-31, 15:03   #2
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Test: worker windows and adjust?
(just a nitpick 0-49 is 50, not 49)
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Old 2012-05-31, 18:31   #3
Dubslow
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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.
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Old 2012-05-31, 19:10   #4
petrw1
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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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Old 2012-05-31, 19:57   #5
treesong
 
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Quote:
Originally Posted by firejuggler View Post
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.
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Old 2012-05-31, 20:04   #6
treesong
 
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Quote:
Originally Posted by petrw1 View Post
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.
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Old 2012-05-31, 20:13   #7
treesong
 
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Quote:
Originally Posted by petrw1 View Post
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.
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Old 2012-05-31, 20:17   #8
treesong
 
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Quote:
Originally Posted by petrw1 View Post
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!!!
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Old 2012-05-31, 22:40   #9
Prime95
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Quote:
Originally Posted by treesong View Post
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 :)

Last fiddled with by Prime95 on 2012-05-31 at 22:40
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Old 2012-05-31, 22:59   #10
kracker
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Quote:
Originally Posted by Prime95 View Post
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 :)
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Old 2012-06-16, 01:15   #11
ixfd64
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A scrollable MDI would be quite useful in this case: http://www.mersenneforum.org/showthread.php?t=16083
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