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Old 2008-12-06, 02:17   #1
srwongcm
 

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Default What is the requirement

What is the requirement of CPU for the LL test?

Why my computer always trial factoring 2 to power 64 to 65?
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Old 2008-12-06, 05:26   #2
Uncwilly
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I would limit the CPU to those that can produce one result within 2 months. Currently a P4 or better would be ok.

The factoring is done from one bit level up to the next. See this page:
http://v5www.mersenne.org/various/math.php
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Old 2008-12-06, 05:36   #3
petrw1
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I too am curoius what the criteria are for selecting various work types.

You can personally select your work type from the Test... Worker Windows... menu ... but before you do let me tell you what I am seeing across my PCs ( various hardware and varying assignments) as a gauge for you to determine how long you are willing to wait for results:

Intel Q9550: Each core can complete a LL test of a 47M number in about 35 days. LL on 23M number in about 7 days.
Intel Duo Q6600: Each core can complete a 23M DC in about 9 days
Intel PIV 3.4 Ghz: Can complete a LL on a 28M in about 16 days. LL on 47M in about 50 days.
Intel PIV 2.4 Ghz Hyper Thread: Can complete a LL on a 28M in about 18 days. LL on 47M in about 60 days.
Intel PIV 2.8 Ghz: Can complete a LL on a 28M in about 20 days. LL on 47M in about 65 days.

(Note: 47M means a 47 Million Exponent.)

Last fiddled with by petrw1 on 2008-12-06 at 05:41
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Old 2008-12-06, 16:34   #4
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Quote:
1GHz and faster computers get first-time primality tests. These tests require the most work and have the best chance of finding a new Mersenne prime. Computers between PII-233 and 1 GHz usually get double-check assignments. These assignments do not take as long and can find a Mersenne prime only if the original test had a problem. The slowest computers are usually assigned factoring work.
http://www.mersenne.org/various/works.php
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Old 2008-12-06, 17:16   #5
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I am afraid that even if the page was recently updated that part was not : a PIII-600 would need about 4 month to complete a 23M double-check and 16 month to complete a 42M first time test...

Jacob

Last fiddled with by S485122 on 2008-12-06 at 20:40 Reason: added data about first time check
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Old 2008-12-06, 18:25   #6
petrw1
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Can someone confirm this. It seems outdated:
Quote:
1GHz and faster computers get first-time primality tests. These tests require the most work and have the best chance of finding a new Mersenne prime.
Most first time tests now are in the 47M+ range.
My PIV-2.4 just timed as needing 60 days for a 47M LL. According to the benchmarks page a 1Ghz can be 5-8 times slower so this same assignment could take over a year.
Quote:
Computers between PII-233 and 1 GHz usually get double-check assignments. These assignments do not take as long and can find a Mersenne prime only if the original test had a problem.
My PIII-866 just timed as needing 90 days for a 23M DC.
The benchmark page has PII-300 but no PII-233. The PII-333 is about 3 or 4 times slower than my PIII-866. So even it would take again over a year for this 23M DC.
Quote:
The slowest computers are usually assigned factoring work
I have to believe there are very few people still running anything slower than a PII-233, which would make the TF pool pretty darm small and slow.
Even when I converted my PIII-866 to v5 and asked for TF (what is supposed to get assigned to the slowest computers) Prime95 told me my PC was too slow and instead assigned me TF-LMH.
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Old 2008-12-06, 19:51   #7
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These are all adjustable on the server. Look at the cpu properties web page - you'll see something called 'p4 effective speed'.

You'll need 1.4GHz p4 speed to get first-time LL.
You'll need 1.0GHz p4 speed to get double-checks.

There are also requirements on getting a "preferred" assignment (one of the smallest available).

The 1.4GHz value should probably be raised to 2.0 GHz or so.
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Old 2008-12-06, 21:10   #8
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Quote:
Originally Posted by Prime95 View Post
There are also requirements on getting a "preferred" assignment (one of the smallest available).
I'd like to get on that list some day.

Quote:
The 1.4GHz value should probably be raised to 2.0 GHz or so.
I would tend to agree. A 1.4 would probably take 4-5 months on current LL tests.
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Old 2008-12-06, 22:46   #9
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Quote:
Originally Posted by petrw1 View Post
I'd like to get on that list some day.
Everyone is on that list - as long as your computer is fast enough and you've completed some number of LL tests reliably. I think you need a reliability level above 0.9 and a confidence level above 2 and a p4 effective speed above 2GHz. Of course, all those quantities are adjustable.
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