P-1 factoring anyone? - Page 97

KyleAskine · 2012-01-05, 21:33

Quote:

Originally Posted by James Heinrich

You can get an approximate idea of how many GHz-days/day your GPU can process here.

Not us AMD folk!!

henryzz · 2012-01-05, 21:56

Quote:

Originally Posted by James Heinrich

Depends how you define "feasible", but I'd say roughly 15 years to be able to LL M999M on common hardware in approximately 1 month.

Is that based on one core or more? Do we have any clue how many cores cpus will have then? Will Prime95 be parallel enough by then to usefully run a single test on 128 cores(maybe possible by then?)?

James Heinrich · 2012-01-05, 22:11

Quote:

Originally Posted by KyleAskine

Quote:

Originally Posted by James Heinrich

You can get an approximate idea of how many GHz-days/day your GPU can process here.

Not us AMD folk!!

All mfakto users are encouraged to email me benchmarks including 4 critical pieces of data running a single instance of mfakto:
1) GPU model + clockspeed
2) assignment (exponent, startingbits, endingbits)
3) wall time it took to process the assignment
4) average GPU usage
Average SievePrimes value, and CPU model/clockspeed are useful as well, but not required.

Once I get enough data then AMD users can also benefit from that page.

Dubslow · 2012-01-05, 23:39

Quote:

Originally Posted by henryzz

Is that based on one core or more? Do we have any clue how many cores cpus will have then? Will Prime95 be parallel enough by then to usefully run a single test on 128 cores(maybe possible by then?)?

I'm not sure it can get any more parallel than it is now, which isn't very much. (Unless that guy who was writing a IBDWFFT for GPU comes back from being afk...)

timbit · 2012-01-07, 07:32

Hi,

I found a large factor for M77999869:

p61 = 1815615329758341197381057535338581863482459211614518833203801

123-bit number

= p24 195493151840292702688361 *
p37 9287360261302658846450143394743421041

factoring of p24-1 =
2^3 * 5 * 43 * 136093 * 10707139 * 77999869

factoring of p37-1 =
2^4 * 3^5 * 5 * 7 * 17 * 283 * 12239 * 14033 * 45377 * 23336543 * 77999869

This is the biggest one I've found so far.

James Heinrich · 2012-01-07, 13:56

Quote:

Originally Posted by timbit

123-bit number

Nice find.
To clarify, your 61-digit composite factor is 200 bits, but the larger of the two prime factors is still 123-bit.
http://mersenne-aries.sili.net/M77999869

Dubslow · 2012-01-07, 15:17

Does Prime95 report the composite factor, or does it realize that it's composite before submission?

James Heinrich · 2012-01-07, 15:20

Quote:

Originally Posted by Dubslow

Does Prime95 report the composite factor, or does it realize that it's composite before submission?

Prime95 finds and reports the composite factor; PrimeNet determines that it's composite upon submission (as does my site).

aketilander · 2012-01-24, 14:23

I wonder how to calculate the largest possible factor of a Mersenne number that could be found by the P-1 Brent-Suyama extension as it is used in prime95. That is if:

Exponent = M
B1 = B1
B2 = B2

Which is the largest possible factor that could be found by the Brent-Suyama extension?

Maybe a calculator could be included in http://mersenne-aries.sili.net/

James Heinrich · 2012-01-24, 14:41

Quote:

Originally Posted by aketilander

Which is the largest possible factor that could be found by the Brent-Suyama extension?

What is the largest factor that could be found without it? Very large factors could be found, if they existed and were improbably-smooth. It's very easy to examine a factor and determine either the needed bounds to find it, or whether given bounds would find the factor, but I don't think there's any particular limit to the size of factors that could be found with any particular bounds (? someone correct me if I'm wrong, please).

Quote:

Originally Posted by aketilander

Maybe a calculator could be included in http://mersenne-aries.sili.net/

I'd be happy to, if someone can explain the math in very simple words that I could understand.

(Mr. P-1 had given me a nice explanation of the Brent-Suyama extension, but I don't know what to do with that...

)

petrw1 · 2012-01-24, 16:55

Quote:

Originally Posted by Dubslow

I'm not sure it can get any more parallel than it is now, which isn't very much.

When I run 4 25M DC tests on my i5-750 (which is now 3 year old technology) OC'd to 3200 my per iteration time for each core in just over .020 seconds.

When I use 3 cores in parallel for 1 DC the time is just under .007 seconds.
The remaining core DC time drops slightly to about .0197.

I am getting about 96% effeciency on the 3 cores in parallel
and about 102% efficiency in the 4th cores.

Seems like pretty decent parallelization to me.

It still quite good with all 4 cores on 1 DC; the per iteration time drops to about .0056 which is close to 90% efficiency.

2012-01-07, 07:32	#1061
timbit Mar 2009 2·3 Posts	Large p-1 factor found Hi, I found a large factor for M77999869: p61 = 1815615329758341197381057535338581863482459211614518833203801 123-bit number = p24 195493151840292702688361 * p37 9287360261302658846450143394743421041 factoring of p24-1 = 2^3 * 5 * 43 * 136093 * 10707139 * 77999869 factoring of p37-1 = 2^4 * 3^5 * 5 * 7 * 17 * 283 * 12239 * 14033 * 45377 * 23336543 * 77999869 This is the biggest one I've found so far.

2012-01-24, 14:23	#1065
aketilander "Åke Tilander" Apr 2011 Sandviken, Sweden 2×283 Posts	Brent-Suyama extension I wonder how to calculate the largest possible factor of a Mersenne number that could be found by the P-1 Brent-Suyama extension as it is used in prime95. That is if: Exponent = M B1 = B1 B2 = B2 Which is the largest possible factor that could be found by the Brent-Suyama extension? Maybe a calculator could be included in http://mersenne-aries.sili.net/

2012-01-07, 15:17	#1063
Dubslow Basketry That Evening! "Bunslow the Bold" Jun 2011 40<A<43 -89<O<-88 16065₈ Posts	Does Prime95 report the composite factor, or does it realize that it's composite before submission?