20211202, 17:33  #23 
Aug 2020
79*6581e4;3*2539e3
601 Posts 
Thanks, I had thought about using the GPU since at Primegrid sieving Proth numbers with GPU is much faster than any CPU. The reason I didn't was that I only have a GTX 760 and a GTX 1660. The 760 is quite slow and not useful. The 1660 might be ok, but I prefer to use it for Wieferich/WallSunSun search currently and as Happy said, it'd need to be really fast to compete against the 12 cores of the Ryzen 9 3900X.
Btw, hijack all you want, I'm glad to hear about such things. 
20211204, 06:45  #24  
"AMD YES!"
Jan 2020
Bellevue, WA
122_{8} Posts 
Quote:


20211206, 09:53  #25 
Aug 2020
79*6581e4;3*2539e3
601 Posts 
While we're on the topic of sieving on GPU, did anyone try colab sessions for it? I don't have any experience with it, just began copy&pasting GPU72 code which seems to run fine. Is there a similar "fire&forget" available for srsieve2cl?

20220119, 10:36  #26 
Aug 2020
79*6581e4;3*2539e3
601_{10} Posts 
No new primes, just another status update:
No sieving was done since the last update. All n < 5,600,000 have now been checked. No prime since more than 5M candidates, low weight indeed. :) Since the FFT size grew to 640K with n > 5.6M, the 64 MB L3 cache of the Ryzen 9 3900x ran out when testing 12 numbers simultaneously. Initially I ran six 2threaded LLR instances, but noticed that two of them were about 30% slower than the other four. The reason being the special layout of the processor. There are four socalled CCDs with 16MB L3 cache each. And since each CCD houses three cores, that means that two of the LLR instances ran on two separate CCDs. So I switched to four 3threaded LLR instances occupying a single CCD each. Maybe special constructs like 4 2threaded and 4 singlethreaded LLRs would lead to a higher throughput, I didn't run any tests. Smallest LLRtest currently running: n = 5.62M FFT = 640K duration = 4060 s / test digits = 1.69M Caldwell entry rank: 241 Largest LLRtest currently running: n = 5.65M FFT = 640k duration = 4090 s / test digits = 1.70M Caldwell entry rank: 238 
20220705, 11:18  #27 
Aug 2020
79*6581e4;3*2539e3
601 Posts 
Long time no update...
After a pause the tests are now running on a 12core i910920x with 32 GB RAM and 20 MB L3 cache under Ubuntu 22.04 LTS. It supports AVX512 which not only gives a nice speedup but also decreased the FFT from 640K to 588K (I assume that's what caused it). Since I'm now only running 2 simultaneous tests, I can comfortably run each one singlethreaded. All n < 5,800,000 have been checked for primality now. No new primes. Largest known prime: n = 485014 (146010 digits) Some stats for the 4,100,000 < n 10,000,000 range:
Sieving Recently sieved: 800E12 < p < 825E12 Software: sr1sieve 1.4.7 Factors found: 77 Largest factor found: 824937311469287 (15 digits)  1281979 * 2^6579962 + 1 LLR Currently testing: 5,800,000 <= n < 5,820,000 Software: LLR2 1.1.1 FFT = 588K duration = 7400 s / test digits = 1.74M  1.75M Caldwell entry rank: 249 Last fiddled with by bur on 20220705 at 11:22 
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