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

henryzz 2011-04-09 10:48

[QUOTE=cheesehead;257998]Module gwnum.h in the Windows source has the definition

#define MAX_PRIME_SSE2 596000000L /* SSE2 bit limit */

595999993 is probably the largest prime < 596000000

LL, ECM and P-1 all use FFTs, and 596000000 is the maximum exponent the FFTs can now handle AFAIK.

Perhaps the higher exponents were processed with a Mac version of the software rather than a Windows version.[/QUOTE]
AFAIK the non-SSE2 code supports higher exponents than SSE2 code. The sacrifice was thought worthwhile at the time.:smile:

Mr. P-1 2011-04-09 11:42

[QUOTE=xilman;257997]To compensate, rate the top 1000 by the size of P-1 after division by all powers of the Mersenne exponent.[/QUOTE]

Why all powers? Why not one power?

[QUOTE]Note that this proposal scales down composite P-1 factors also.[/QUOTE]

Composite factors should be resolved into their constituent primes.

cheesehead 2011-04-10 05:31

[QUOTE=henryzz;258001]AFAIK the non-SSE2 code supports higher exponents than SSE2 code.[/QUOTE]I haven't found the definition of MAX_PRIME yet.

xilman 2011-04-10 06:40

[QUOTE=Mr. P-1;258004]Why all powers? Why not one power?



Composite factors should be resolved into their constituent primes.[/QUOTE]Purely to give a way of dealing with composites. If they are factored, multiple powers are not the issue.

Paul

axn 2011-04-10 08:19

[QUOTE=xilman;258069]Purely to give a way of dealing with composites. If they are factored, multiple powers are not the issue.

Paul[/QUOTE]

Slighly confused. Are you suggesting that if C = P1*P2 be a composite factor of a mersenne M(p), then C-1 will be divisible by p^2?

Obviously (P1-1)*(P2-1) will be divisible by p^2, but, in general, C-1 won't be.

xilman 2011-04-10 09:06

[QUOTE=axn;258072]Slighly confused. Are you suggesting that if C = P1*P2 be a composite factor of a mersenne M(p), then C-1 will be divisible by p^2?

Obviously (P1-1)*(P2-1) will be divisible by p^2, but, in general, C-1 won't be.[/QUOTE]You're right and I was confused (read: wrong).

The correct approach, IMO, is to report only prime factors and to scale them by dividing by p.

Division by p rewards hard work, because higher B1 & B2 gives a higher chance of finding a factor, and good luck.

Paul

drh 2011-04-13 11:00

[QUOTE=petrw1;257690]And if I put my entire (albeit meagre) team of P-1 capable PCs (3 Quads and 6 Duals and 1 P4=25 cores) I estimate I could complete only about 10 or 12 per day or 5 - 6%.

Mind you, all 4 cores of a Quad on P-1 could be quite taxing.[/QUOTE]

I now have 5 cores running P-1's and over the last 30 days I'm averaging 2.6 per day in the 53M range all in the 4.6 - 4.7 GHz-Day range.

science_man_88 2011-04-13 11:37

[QUOTE=drh;258387]I now have 5 cores running P-1's and over the last 30 days I'm averaging 2.6 per day in the 53M range all in the 4.6 - 4.7 GHz-Day range.[/QUOTE]

I remember being told by someone that p-1 would only take me 7 days but I stopped it ~1 day in because it had only done like 3% (100/3 =33.3 days not 7)

petrw1 2011-04-13 15:05

[QUOTE=science_man_88;258390]I remember being told by someone that p-1 would only take me 7 days but I stopped it ~1 day in because it had only done like 3% (100/3 =33.3 days not 7)[/QUOTE]

Depends completely on what CPU you are running on and how much RAM you allocate.

I have a i5-750 that will complete a P-1 in the 50M range in 31 hours and a PIV 2.4 Ghz that takes over 100 hours.

petrw1 2011-04-13 15:30

[QUOTE=drh;258387]I now have 5 cores running P-1's and over the last 30 days I'm averaging 2.6 per day in the 53M range all in the 4.6 - 4.7 GHz-Day range.[/QUOTE]

Is that 5 cores on 1 PC? Or 1 core on each of 5 PC's or a combination of such?

If you have more than 1 core on a PC doing P-1 do you notice any conflict for CPu resources; for example, do the run times drop noticeably if there are more than 1 cores doing stage 2?

drh 2011-04-13 16:53

[QUOTE=petrw1;258415]Is that 5 cores on 1 PC? Or 1 core on each of 5 PC's or a combination of such?

If you have more than 1 core on a PC doing P-1 do you notice any conflict for CPu resources; for example, do the run times drop noticeably if there are more than 1 cores doing stage 2?[/QUOTE]

Here is what I'm doing right now -

1 Intel Core i5 M 540 @ 2.53GHz 4Gig RAM -- (1 Core P-1 & 1 Core mafktc)
1 Intel Core i7 Q 720 @ 1.60GHz 8Gig RAM -- (2 Cores P-1 & 2 Cores LL)
1 Intel Core2 Quad Q8400 @ 2.66GHz 8Gig RAM -- (2 Cores P-1 & 2 Cores LL)

The memory on the systems running (2 P-1's) automatically adjusts when they are both in stage 2, but the throughput remains the same, as well as the throughput of the LL's. I'm contemplating trying (3 P-1's) at a time, and if I do, I'll let you know those results as well.


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