mfaktc: a CUDA program for Mersenne prefactoring

[drh]

Originally Posted by drh

Thanks, will do this evening.

Doug

Well, it partially worked. The 4 exponents in question only had 1 of four mfaktc TF's accepted. Maybe it was because I had manually changed the bit assignments from 69-70 to 69-73 and ran them individually?

The exponents have been released, and without an assignment code, they will not be accepted, unless there is a way around that ... down to 42 lost GHZ-days.

Doug

[vsuite]

How about trying to reserve the same ones again by limiting the trial factoring range to what you are looking for?

[Bdot]

Originally Posted by TheJudger

Hello,

here is mfaktc 0.17!

• Users with "fast CPU + slow GPU" can try to enable AllowSleep in mfaktc.ini. This allows the CPU to sleep instead of running a busyloop if the CPU has to wait for the GPU
• replaced compiletime option "THREADS_PER_GRID_MAX" with the runtime option "GridSize" (mfaktc.ini)
  • maximum "threads per grid" is now 2²⁰ (was 2²¹), default value is the same as before
  • maximum SievePrimes increased from 100.000 to 200.000
  • lower GridSize might increase the usability of your GUI while running mfaktc at the cost of slightly lower performance
• no change in performance compared to 0.16p1

Thanks Oliver,

works like a charm! The increased SievePrimes adds about 5% performance for me as ~5% less FCs are to be evaluated. And CPU load is now just 30-50% of one core. I like it!

B.

PS: I now have some rudimentary OpenCL version using some of your code running on my ATI-GPU. It already found a few factors (proof of concept OK) but I just can't get it to utilize the GPU above ~10% ... work in progress.

[drh]

Originally Posted by vsuite

How about trying to reserve the same ones again by limiting the trial factoring range to what you are looking for?

Tried that as well, but PrimeNet responded saying that those exponents were not available ... probably since I had taken them up to 73 bits, 2 more than PrimeNet was expecting.

Oh well, lesson learned.

[Christenson]

In discussion wih Prime95, GW told me that although mfaktc splits results to single bit levels, the server will take a result with multiple bit levels. I haven't encountered the need to do that, but I've also been reporting mfaktc results on relatively fresh logins.

[drh]

Tonight while I was uploading some more results, I got a timeout. Eventually, almost everything got uploaded correctly, except this one exponent ...

no factor for M76120789 from 2^69 to 2^70 [mfaktc 0.16p1-Win barrett79_mul32]
no factor for M76120789 from 2^70 to 2^71 [mfaktc 0.16p1-Win barrett79_mul32]
no factor for M76120789 from 2^71 to 2^72 [mfaktc 0.16p1-Win barrett79_mul32]
M76120789 has a factor: 5666251615825315865351
found 1 factor(s) for M76120789 from 2^72 to 2^73 [mfaktc 0.16p1-Win barrett79_mul32]

I got credit for everything except the factor ...
Guess I can reserve it again and run the bit level again?

Update: can't reserve that exponent ... no assignment available.

Thanks,
Doug

[nucleon]

Originally Posted by drh

M76120789 has a factor: 5666251615825315865351
found 1 factor(s) for M76120789 from 2^72 to 2^73 [mfaktc 0.16p1-Win barrett79_mul32]

I got credit for everything except the factor ...
Guess I can reserve it again and run the bit level again?

Update: can't reserve that exponent ... no assignment available.

Thanks,
Doug

False positive maybe?

You didn't get credit as it's a false result?

You can try to submit those 2 lines again manually. I have a 'free spot' on my GPU in 20mins, I'll run the test and see what result I get. I'll post result here. I won't attempt to get credit.

-- Craig

[ckdo]

Originally Posted by nucleon

False positive maybe?

5666251615825315865351 = 2×5^2×7×11×13×83×17918861×76120789+1.
That was easy.

Originally Posted by drh

I got credit for everything except the factor ...
Guess I can reserve it again and run the bit level again?

Update: can't reserve that exponent ... no assignment available.

You will get credit for the manual submission of any new factors even if the exponent in question is not assigned to you.

You will also receive no-factor credit if the exponent is assigned to you for something other than TF.

[nucleon]

Okay I got same answer

M76120789 has a factor: 5666251615825315865351
found 1 factor(s) for M76120789 from 2^72 to 2^73 (partially tested) [mfaktc 0.16-Win barrett79_mul32]

-- Craig

[axn]

Originally Posted by drh

Tonight while I was uploading some more results, I got a timeout. Eventually, almost everything got uploaded correctly, except this one exponent ...

no factor for M76120789 from 2^69 to 2^70 [mfaktc 0.16p1-Win barrett79_mul32]
no factor for M76120789 from 2^70 to 2^71 [mfaktc 0.16p1-Win barrett79_mul32]
no factor for M76120789 from 2^71 to 2^72 [mfaktc 0.16p1-Win barrett79_mul32]
M76120789 has a factor: 5666251615825315865351
found 1 factor(s) for M76120789 from 2^72 to 2^73 [mfaktc 0.16p1-Win barrett79_mul32]

I got credit for everything except the factor ...
Guess I can reserve it again and run the bit level again?

Update: can't reserve that exponent ... no assignment available.

Thanks,
Doug

Have you tried to just resubmit the result -- just the factor line? It is a legitimate result. No need to redo the range.

[TheJudger]

Originally Posted by drh

Tonight while I was uploading some more results, I got a timeout. Eventually, almost everything got uploaded correctly, except this one exponent ...

no factor for M76120789 from 2^69 to 2^70 [mfaktc 0.16p1-Win barrett79_mul32]
no factor for M76120789 from 2^70 to 2^71 [mfaktc 0.16p1-Win barrett79_mul32]
no factor for M76120789 from 2^71 to 2^72 [mfaktc 0.16p1-Win barrett79_mul32]
M76120789 has a factor: 5666251615825315865351
found 1 factor(s) for M76120789 from 2^72 to 2^73 [mfaktc 0.16p1-Win barrett79_mul32]

I got credit for everything except the factor ...
Guess I can reserve it again and run the bit level again?

Update: can't reserve that exponent ... no assignment available.

Thanks,
Doug

Just try again to submit the factor. If you ran into a timeout during upload of results than the primenet server typically missed some of your results.

Originally Posted by nucleon

False positive maybe?

Luigis (ET_) defactor (using libgmp) with slightly modifications agrees the factor.

o@Lysithea:~> ./defactor.exe 76120789 5666251615825315865351

The factor 5666251615825315865351 divides 2^76120789 -1! K = 37218818211575
The factor 5666251615825315865351 is probably prime

Oliver