[QUOTE=James Heinrich;284940]
You can get an approximate idea of how many GHz-days/day your GPU can process [url=http://mersenne-aries.sili.net/mfaktc.php]here[/url].[/QUOTE]

Not us AMD folk!!

[QUOTE=James Heinrich;284943]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.[/QUOTE]
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?)?

[QUOTE=KyleAskine;284953][QUOTE=James Heinrich;284940]You can get an approximate idea of how many GHz-days/day your GPU can process [url=http://mersenne-aries.sili.net/mfaktc.php]here[/url].[/QUOTE]Not us AMD folk!![/QUOTE]All mfakto users are encouraged to email me benchmarks including 4 critical pieces of data [b]running a single instance of mfakto[/b]:
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. :smile:

[QUOTE=henryzz;284957]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?)?[/QUOTE]

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...)

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.

[QUOTE=timbit;285224]123-bit number[/QUOTE]Nice find.
To clarify, your 61-digit composite factor is 200 bits, but the larger of the two prime factors is still 123-bit.
[url]http://mersenne-aries.sili.net/M77999869[/url]

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

[QUOTE=Dubslow;285262]Does Prime95 report the composite factor, or does it realize that it's composite before submission?[/QUOTE]Prime95 finds and reports the composite factor; PrimeNet determines that it's composite upon submission (as does my site).

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 [URL]http://mersenne-aries.sili.net/[/URL]

[QUOTE=aketilander;287115]Which is the largest possible factor that could be found by the Brent-Suyama extension?[/quote]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=aketilander;287115]Maybe a calculator could be included in [URL]http://mersenne-aries.sili.net/[/URL][/QUOTE]I'd be happy to, if someone can explain the math in very simple words that I could understand. :cmd:
([i]Mr. P-1[/i] had given me [url=http://www.mersenneforum.org/showpost.php?p=280258&postcount=915]a nice explanation of the Brent-Suyama extension[/url], but I don't know what to do with that... :help::cry:)

[QUOTE=Dubslow;284970]I'm not sure it can get any more parallel than it is now, which isn't very much.[/QUOTE]

:confused:

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.