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-   -   P-1 factoring anyone? (https://www.mersenneforum.org/showthread.php?t=11101)

delta_t 2011-10-21 03:05

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?

Dubslow 2011-10-21 03:42

[QUOTE=delta_t;275232]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?[/QUOTE]
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.

kladner 2011-10-21 04:34

[QUOTE=Dubslow;275235]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.[/QUOTE]

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.

delta_t 2011-10-21 04:37

[QUOTE=Dubslow;275235]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.[/QUOTE]

Yeah I saw that earlier. Unfortunately I don't have any numbers either. I'm thinking of trying a test of it though.

Dubslow 2011-10-21 04:58

[QUOTE=kladner;275238]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.[/QUOTE]
I meant the data about the effectiveness of B-S finding factors.

kladner 2011-10-21 05:45

[QUOTE=Dubslow;275240]I meant the data about the effectiveness of B-S finding factors.[/QUOTE]

Oops. OK.

Dubslow 2011-10-21 06:23

S'all good. :omg:
Sorry, that's the problem with the interblags, a.k.a. wobitubes, is that it seems so harsh
:down: :loco:
:huh: :mad:
:cmd: :ermm:
:hello: :wink:
:lol: :mellow:
:chevy: :sick:
:ernst: :big grin:
:yawn: :nuke:
:sleep: :evil:
:popcorn: :rofl:
:love: :flex:
:toot: :squash:


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

James Heinrich 2011-10-22 20:39

[QUOTE=KingKurly;275046]Some day, I'll catch up to the LL wavefront. Maybe. :wink:[/QUOTE]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.

James Heinrich 2011-10-22 20:46

[QUOTE=Brain;275058]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][QUOTE=kladner;275081]It certainly seems that P-1 will gulp down as much as it is allowed.[/QUOTE]To do a proper P-1 on a [url=http://mersenne-aries.sili.net/prob.php?exponent=54000000&b1=595000&b2=14875000&factorbits=&K=1&C=-1&submitbutton=Calculate]54M range exponent[/url], 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).

Mr. P-1 2011-10-22 21:59

[QUOTE=James Heinrich;275359]To do a proper P-1 on a [url=http://mersenne-aries.sili.net/prob.php?exponent=54000000&b1=595000&b2=14875000&factorbits=&K=1&C=-1&submitbutton=Calculate]54M range exponent[/url], 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]

[QUOTE=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;[/QUOTE]

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.

James Heinrich 2011-10-22 22:56

[QUOTE=Mr. P-1;275364]That's the minimum recommended, not the minimum needed to do any stage 2 at all, right?[/QUOTE]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 [b]300MB[/b] of memory.
Assuming no factors below 2^71 and 2 primality tests saved if a factor is found.
Optimal bounds are [b]B1=535000, B2=7222500[/b]
Chance of finding a factor is an estimated [b]4.19%[/b]
[i]effort = [b]2.76GHz-days[/b][/i][/quote][quote]Optimal P-1 factoring of M54952927 using up to [b]10000MB[/b] of memory.
Assuming no factors below 2^71 and 2 primality tests saved if a factor is found.
Optimal bounds are [b]B1=580000, B2=13340000[/b]
Chance of finding a factor is an estimated [b]4.74%[/b]
[i]effort = [b]3.92GHz-days[/b][/i][/quote]How it plays out in Stage 2 I'm not sure.


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