20230116, 01:53  #45  
Apr 2020
3·317 Posts 
Quote:
The search limit is at least 2^64 now, but log log 2^64 = 3.79 so it's not that surprising we've only found 2. 

20230116, 13:10  #46  
Feb 2017
Nowhere
3×2,113 Posts 
Quote:
Quote:
I should have checked the value of log(log(10^15)) before posting. I realized this some hours after I'd posted. 

20230119, 02:04  #48 
Aug 2002
Buenos Aires, Argentina
2^{2}×3×5^{3} Posts 
I'm running P1 on the cofactor with B1 = 10M, B2 = 300M. At this moment the computer is running step 1 which is 67.28% complete. At this rate, step 2 will start on Friday.

20230119, 23:33  #49 
Dec 2022
313 Posts 
This is well beyond what anyone could expect  even though I asked the question I didn't expect much computational effort put into it, and I'd consider this factor of interest only if shown PRP. But I'd have to say that B2 should be higher if you are going to do P1 to extra length.
You are running 30.8, and limiting the B2 manually is rarely a good idea with the new algorithm, in which B2 increases faster than linearly with time. If you must set it manually I'd expect it should be at least 100:1, as I tried to achieve even with the old algorithm in such cases. 
20230120, 01:46  #50 
Aug 2002
Buenos Aires, Argentina
2^{2}·3·5^{3} Posts 
The speedup of the second step depends not only on the amount of RAM but also on the exponent being considered. If you worked with a 7digit exponent the ratio B2/B1 could be a lot larger.
At this moment step 1 is 86.11% complete. 
20230120, 07:41  #51 
"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest
7548_{10} Posts 
more precisely I think, the integer number of fftlength size buffers that will fit in the allowed ram. It's not a continuous function of ram/exponent. Fft length is a stepwise function of exponent. So it is a "staircase".
And there could be more to it. I don't recall whether the new prime95 algorithm also has a requirement similar to one that Mlucas P1 has, that the buffer count be an integer multiple of 24 or 40. Last fiddled with by kriesel on 20230120 at 07:45 
20230121, 00:59  #52 
Dec 2022
313 Posts 
I can't answer that last  it should be in the source  but yes, of course it's discrete. Even the old algorithm has discrete 'relative primes', and FFT sizes are discrete. It's just that continuous functions are much nicer approximations, and generally close enough for this work.
But we all know it depends on allocated RAM and on exponent. My supposition was that it also depended on B2, so the optimal B2/B1 (holding memory and exponent fixed) should be increasing with B1. The stage 2/stage 1 runtime ratio for alpertron's runs on this exponent would immediately show whether I'm right (if roughly constant, as with the old algorithm, then I'm wrong). The actual values used by others on small exponents seem to support this. 
20230121, 14:00  #53 
Aug 2002
Buenos Aires, Argentina
5DC_{16} Posts 
I changed B2 to 1G. Now the computer is running step 2 of P1.
It appears that it will finish on Wednesday. 
20230128, 11:57  #54 
Aug 2002
Buenos Aires, Argentina
2^{2}·3·5^{3} Posts 
No prime factor was found using P1 with the bounds noted above.

20230129, 02:42  #55 
Dec 2022
139_{16} Posts 
So we're done with this now? I'm guessing you are tired of it by now and content to leave it there, as am I as my question has been gone over quite sufficiently, and I gratefully accept your contribution to it.
I am still curious about my conjecture on P1, though. 
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