20210212, 20:30  #1 
May 2004
FRANCE
2×3×97 Posts 
llrCUDA version 3.8.3 is released!
Hi All,
I released now a new GPU version of the LLR program on my personal page : jpenne.free.fr No much new feature, but some improvements related to reliability and speed.  By default, all tests on base two numbers use Gerbicz error checking. This is the case for PRP Fermat and SPRP tests as in Prime95 or Mprime, but also for the deterministic prime tests of Proth numbers. LLR tests on Riesel numbers are only done after a positive Fermat PRP result. Also, if b==2, k==+1 and abs(c)==1, a random shift on the PRP base is done. It is especially interesting for the prime test of Gaussian Mersenne norms. Like the previous versions, this code is fully C and C++ written, no Assembler code. Large numbers (at least 1 mega digits) benefit more from the GPU parallelism, but this program may also be used on smaller positive results for verification... For more details, would you see the Readme.txt file. Please, let me know if you have any problem to run the binary on Linux and/or to build it on your system. I wish you many successes in prime hunting! Best Regards, Jean 
20210212, 22:46  #2 
"Mark"
Apr 2003
Between here and the
198A_{16} Posts 
Any plans for an OpenCL version? I can't run CUDA on AMD.

20210212, 23:16  #3  
Dec 2011
After milion nines:)
3×7×71 Posts 
Quote:


20210213, 07:18  #4 
May 2004
FRANCE
582_{10} Posts 

20210215, 20:09  #5 
May 2004
FRANCE
2·3·97 Posts 
llrCUDA version 3.8.3 Build 2 is released!
Hi All,
While Fermat testing k*b^n+c large numbers with c<0, and Gerbicz error checking activated, the final computation of the residue used a call to the invg() function in the giants.c code. This code being CPU only, it is very time consuming for mega_digits numbers and so, its use must be avoided. That is the only fix done in this new build of llrCUDA. Would you excuse me for this drawback, and Best Regards, Jean 
20210215, 21:05  #6 
"W. Byerly"
Aug 2013
81*2^27974431
5·23 Posts 
Hi, I have a machine with 3 cards: 2x gtx1060 6gb and a 980 ti. How would I ensure that I can run LLRcuda instances on all 3 cards? Just run 3 instances of it?

20210228, 15:28  #7 
Sep 2002
Database er0rr
F93_{16} Posts 
If you have tried llrCuda out please post how well it does. How many AVX2 cores is it equivalent to on a top end nVidia card?

20210228, 15:56  #8 
Random Account
Aug 2009
3731_{8} Posts 

20210303, 02:22  #9 
Jun 2003
Ottawa, Canada
2225_{8} Posts 
What kind of speedup should be expected using llrCUDA compared to using a CPU?
I just tried with a P100 GPU: ABC$a*$b^$c$d 1 2 13377491 31 Using complex rational base DWT and generic reduction, FFT length = 1867776, a = 3 2^1337749131 is not prime. RES64: B7A37D7DABBAAC31. Time : 1614496548690.000 ms. Some kind of bug with time output but it took about 38 hours to complete with the 1 P100 GPU so considerably slower than using a CPU unless I am doing something wrong. This is with beta2 ( Primality Testing of k*b^n+/1 Program  GPU Version 3.8.3 ; linked with CUDA Version 8.0.44 ). 
20210310, 20:32  #10 
May 2004
FRANCE
2×3×97 Posts 
llrCUDA version 3.8.3 Build 3 is released!
Hi All,
When a too large round off error was encountered, the test was restarted from the beginning in "cufft only" mode, which was very penalizing about elapsed time. I fixed that in this new build, so the restart is now from the last saved intermediate file. Sorry for this drawback and Best Regards, Jean 
20210312, 18:10  #11 
Jun 2003
Ottawa, Canada
3·17·23 Posts 
Just did another test using our latest PRP with beta3:
llrCUDA  GPU Version 3.8.3b3 ; linked with CUDA Version 8.0.44 2^1338029827 is a Fermat Probable prime! (4027872 decimal digits) Time : 136632.210 sec. By comparison using 4 threads on an Intel Core i76700K took (for base 3Fermat PRP test): 12456.743 sec. So the GPU version is running about 11 times slower. Is that what you would expect for speed with a fermat number like this? Are there specific types of numbers that should be a lot faster with the GPU code? Last fiddled with by Jeff Gilchrist on 20210312 at 18:11 
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