20211124, 21:21  #12 
"Curtis"
Feb 2005
Riverside, CA
2·3·937 Posts 
Depends on how big B2 is, and how big the input is. Once available, experiment. For inputs from this project, two workers and 50GB may be better but for larger inputs a single worker would be. If memory use is like GMPECM, it scales linearly with input size and also with the squareroot of B2.

20211125, 04:16  #13 
P90 years forever!
Aug 2002
Yeehaw, FL
2·5^{2}·163 Posts 
Prime95 30.8 (prebeta) (FOR P1 USERS ONLY; SMALL EXPONENTS ONLY)
For giggles, I tried P1 on M80071, B1=200M It appears that the code that caps B2 at 999*B1 needs to change.
B2 = 76 billion in under 2 minutes! Code:
[Work thread Nov 24 22:56] M80071 stage 1 complete. 798217228 transforms. Total time: 3795.041 sec. [Work thread Nov 24 22:56] Conversion of stage 1 result complete. 5 transforms, 1 modular inverse. Time: 0.004 sec. [Work thread Nov 24 22:56] Switching to FMA3 FFT length 5K using large pages [Work thread Nov 24 22:56] With trial factoring done to 2^85, optimal B2 is 293*B1 = 58600000000. [Work thread Nov 24 22:56] Using 6791MB of memory. D: 270270, 25920x142152 polynomial multiplication. [Work thread Nov 24 22:56] Stage 2 init complete. 998106 transforms. Time: 31.144 sec. [Work thread Nov 24 22:58] M80071 stage 2 complete. 2815495 transforms. Total time: 101.937 sec. [Work thread Nov 24 22:58] Stage 2 GCD complete. Time: 0.003 sec. [Work thread Nov 24 22:58] M80071 completed P1, B1=200000000, B2=76673707110, Wi8: E437AD7F 
20211125, 05:47  #14  
"Florian"
Oct 2021
Germany
2×89 Posts 
Quote:


20211125, 06:14  #15 
1976 Toyota Corona years forever!
"Wayne"
Nov 2006
Saskatchewan, Canada
5^{2}×211 Posts 
[QUOTE=Prime95;593832]For giggles, I tried P1 on M80071, B1=200M It appears that the code that caps B2 at 999*B1 needs to change.
B2 = 76 billion in under 2 minutes! Code:
... [Work thread Nov 24 22:56] With trial factoring done to 2^85, optimal B2 is 293*B1 = 58600000000. ... Does this have something to do with how much ECM has been done? And...with Stage 2 being so much faster and supported larger values for B2 ... might there be a chance to use it to find more factors of the smallest unfactored? Maybe those under 20,000? Last fiddled with by petrw1 on 20211125 at 06:21 Reason: And... 
20211125, 06:31  #16  
P90 years forever!
Aug 2002
Yeehaw, FL
2·5^{2}·163 Posts 
Quote:
I upped B1 to 250M, fixed the 999x cap. B2 = 4.45 trillion in an hour and a half. Code:
[Work thread Nov 24 23:42] Conversion of stage 1 result complete. 5 transforms, 1 modular inverse. Time: 0.004 sec. [Work thread Nov 24 23:42] Switching to FMA3 FFT length 5K using large pages [Work thread Nov 24 23:42] With trial factoring done to 2^90, optimal B2 is 17811*B1 = 4452750000000. [Work thread Nov 24 23:42] If no prior P1, chance of a new factor is 6.43% [Work thread Nov 24 23:42] Using 6791MB of memory. D: 330330, 31680x136392 polynomial multiplication. [Work thread Nov 24 23:42] Stage 2 init complete. 1225472 transforms. Time: 37.495 sec. [Work thread Nov 25 01:17] M80071 stage 2 complete. 145791133 transforms. Total time: 5680.476 sec. [Work thread Nov 25 01:17] Round off: 0.048828125 [Work thread Nov 25 01:17] Stage 2 GCD complete. Time: 0.003 sec. [Work thread Nov 25 01:17] M80071 completed P1, B1=250000000, B2=4459674999780, Wi8: 6A0ECD7D Quote:


20211125, 11:36  #17  
"University student"
May 2021
Beijing, China
2^{2}·67 Posts 
Quote:
Why is the B2 value below inconsistent with the value above? Also, can Prime95 itself guess the estimated Tlevel when it's offline? More problems: How much can wavefront (107116M) P1 benefit from v30.8? what bounds does it use? Does the larger FFT used in stage 2 hurt throughput? Is it larger than necessary? Can the new algorithm be implemented in ECM and PP1 too? Last fiddled with by Zhangrc on 20211125 at 11:49 

20211125, 15:37  #18  
P90 years forever!
Aug 2002
Yeehaw, FL
1FD6_{16} Posts 
The new stage 2 selects a D value (330330 in this case) and then does batches of D values with a single polynomial multiplication. The new code completes the full batch that is larger than the target B2.
Quote:
Quote:
The larger FFT will hurt stage 2 throughput. More study is required to see if prime95 is switching to a larger FFT sooner than necessary. The new algorithm can be implemented for P+1 and ECM with some difficulty. Reading papers by Montgomery / Silverman / Kruppa / Zimmermann is no easy matter! Last fiddled with by Prime95 on 20211125 at 15:38 

20211125, 16:10  #19 
Oct 2021
U. S. / New York, NY
149 Posts 
Does this mean that more impressive improvements, like you're seeing with tiny exponents, might be possible even at the P1 wavefront if someone has massive RAM (say, 128 or 192 GB) and allocates enough of it?

20211125, 16:52  #20 
Jun 2003
5×1,087 Posts 
Not to the same extent as tiny ones, but more memory you throw at it, the better the gains. So, yes, those kind of very large RAM allocations will be useful.

20211125, 22:31  #21 
P90 years forever!
Aug 2002
Yeehaw, FL
1FD6_{16} Posts 
I found a bug in P1 stage 2 init that may or may not have affected my previous runs. I'm rerunning all my v30.8 stage 2 work. When using 30.8, I recommend saving your completed P1 save files until we are confident the new code is working.
Should you wish to try 30.8, links are below.
Windows 64bit: https://mersenne.org/ftp_root/gimps/p95v308b1.win64.zip Linux 64bit: https://mersenne.org/ftp_root/gimps/...linux64.tar.gz Last fiddled with by Prime95 on 20211126 at 01:05 
20211125, 22:58  #22 
"Lisander Viaene"
Oct 2020
Belgium
109 Posts 
I'll be using 30.8 for redoing P1 in ranges where poor P1 was previously done (in range 8.4M for example)
Currently running the first four of Kriesels recommended P1 'selftest' exponents/bounds. (Though it is intended for selftesting GPU P1 software as I understand it. See: https://www.mersenneforum.org/showpo...8&postcount=31 ) All four exponents seem to have returned the correct factors! (Before editing it out I pointed out in this post that reporting for stage 2 was not working. I now realize reporting wasn't supposed to work, apologies!) Last fiddled with by lisanderke on 20211125 at 23:22 
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