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Old 2011-10-21, 03:05   #705
delta_t
 
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It's been mentioned if enough RAM is dedicated to P-1 that the Brent-Suyama extension would be used at the cost of more time completing the assignment. Do we know what kind of time difference (savings) there would be if the Brent-Suyama extension were not used? It sounds like more P-1 may be able to get done but is that much time really saved?

Last fiddled with by delta_t on 2011-10-21 at 03:09
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Old 2011-10-21, 03:42   #706
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Quote:
Originally Posted by delta_t View Post
It's been mentioned if enough RAM is dedicated to P-1 that the Brent-Suyama extension would be used at the cost of more time completing the assignment. Do we know what kind of time difference (savings) there would be if the Brent-Suyama extension were not used? It sounds like more P-1 may be able to get done but is that much time really saved?
Much of the discussion has been that we don't have a clue as to the answers for these questions. Axn was asking if anybody had data, but so far not.
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Old 2011-10-21, 04:34   #707
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Originally Posted by Dubslow View Post
Much of the discussion has been that we don't have a clue as to the answers for these questions. Axn was asking if anybody had data, but so far not.
I think the results I posted above came about with just shy of 1GB per worker doing P-1. I had 2048MB allocated with 2 workers. But I could be mistaken. These might have happened in the wee hours when 4096MB were available, and I wasn't watching.

Last fiddled with by kladner on 2011-10-21 at 04:36 Reason: Added qualifiers for possible (human) memory flaws.
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Old 2011-10-21, 04:37   #708
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Originally Posted by Dubslow View Post
Much of the discussion has been that we don't have a clue as to the answers for these questions. Axn was asking if anybody had data, but so far not.
Yeah I saw that earlier. Unfortunately I don't have any numbers either. I'm thinking of trying a test of it though.

Last fiddled with by delta_t on 2011-10-21 at 04:38
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Old 2011-10-21, 04:58   #709
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Quote:
Originally Posted by kladner View Post
I think the results I posted above came about with just shy of 1GB per worker doing P-1. I had 2048MB allocated with 2 workers. But I could be mistaken. These might have happened in the wee hours when 4096MB were available, and I wasn't watching.
I meant the data about the effectiveness of B-S finding factors.
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Old 2011-10-21, 05:45   #710
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I meant the data about the effectiveness of B-S finding factors.
Oops. OK.
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Old 2011-10-21, 06:23   #711
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S'all good.
Sorry, that's the problem with the interblags, a.k.a. wobitubes, is that it seems so harsh














Weeeeeeeeeeeeeeeeeeeeeeeeeeeee!!!!!!!!!!!
</shit>
<thread>

Last fiddled with by Dubslow on 2011-10-21 at 06:25
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Old 2011-10-22, 20:39   #712
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Originally Posted by KingKurly View Post
Some day, I'll catch up to the LL wavefront. Maybe.
I'm also doing the same thing, and definite progress is being made. 6 months ago there was stragglers down to about 30M, we're now cleaned up to 47.4M. Of course, new assignments become available all the time as older first-time LLs with no P-1 come in, but we'll keep cleaning them up. I generally run my "near-current" P-1s with 2 tests saved, and re-done old (e.g. 10M range) with 3 tests saved.
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Old 2011-10-22, 20:46   #713
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Quote:
Originally Posted by Brain View Post
256MB are not enough for current P-1 assignments. PrimeNet will assign other work then. Give 512MB per core a try. I'm happy with that.
Quote:
Originally Posted by kladner View Post
It certainly seems that P-1 will gulp down as much as it is allowed.
To do a proper P-1 on a 54M range exponent, the minimum RAM requirement is somewhere around 466MB (so 512MB is reasonable); a "generous" allocation would be about 1400MB; and Prime95 should be able to use up to around 11GB (if processing all stage2 relative primes in one pass).
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Old 2011-10-22, 21:59   #714
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Quote:
Originally Posted by James Heinrich View Post
To do a proper P-1 on a 54M range exponent, the minimum RAM requirement is somewhere around 466MB (so 512MB is reasonable); a "generous" allocation would be about 1400MB; and Prime95 should be able to use up to around 11GB (if processing all stage2 relative primes in one pass).
Quote:
Originally Posted by http://mersenne-aries.sili.net/prob.php?exponent=54000000&b1=595000&b2=14875000&factorbits=&K=1&C=-1&submitbutton=Calculate
Recommended RAM allocation: min=466MB; good=1,387MB; max=11,340MB; insane=55,577MB;
That's the minimum recommended, not the minimum needed to do any stage 2 at all, right?

Given that half of all exponents never get any stage 2 at all, a machine with 300MB available (the minimum needed to get a P-1 assignment) will on average do a better P-1 than if this task were left to the LL-testing machine.
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Old 2011-10-22, 22:56   #715
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Originally Posted by Mr. P-1 View Post
That's the minimum recommended, not the minimum needed to do any stage 2 at all, right?
Min/good/max/insane memory values are estimated amounts required to process 8/48/480/2400 relative primes respectively. I'm not sure what Prime95 would do with 300MB for a 54M P-1 assignment. Probably worth a quick experiment if you're curious. Just starting stage1 shows this:
Quote:
Optimal P-1 factoring of M54952927 using up to 300MB of memory.
Assuming no factors below 2^71 and 2 primality tests saved if a factor is found.
Optimal bounds are B1=535000, B2=7222500
Chance of finding a factor is an estimated 4.19%
effort = 2.76GHz-days
Quote:
Optimal P-1 factoring of M54952927 using up to 10000MB of memory.
Assuming no factors below 2^71 and 2 primality tests saved if a factor is found.
Optimal bounds are B1=580000, B2=13340000
Chance of finding a factor is an estimated 4.74%
effort = 3.92GHz-days
How it plays out in Stage 2 I'm not sure.
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