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Old 2021-10-10, 16:16   #17
kriesel's Avatar
Mar 2017
US midwest

23·739 Posts
Default V20.1.x P-1 run time scaling


Based on very limited data, run time scaling is approximately p2.2, for typical recommended bounds, in line with expectations from other applications and from first principles. Run time scaling for Mlucas v20.1 on a dual-xeon-e5-2697v2 system on Ubuntu atop WSL & Windows 10 is consistent with OBD P-1 factoring whole attempts of ~10 months standalone duration, ~15 months with other usual loads. Running stage 2 in parallel on multiple systems can be used to ensure OBD P-1 completion in under a year. (Note the fit to points including a 10M exponent is inaccurate, because that point was run with 8 cores, unlike 16 for the others.)

When selecting exponents for run-time scaling tests, I recommend at least one with a known factor that should be found with usual bounds. That goes first to anchor the low end of the scaling. M10000831 works well. Widely spaced other exponents of use to GIMPS compose the rest; current first-test wavefront ~107M, ~220M, 332M (100Mdigit), & higher (~500M-700M). Running them in that order allows a scaling fit to develop in a spreadsheet with the least compute time expenditure. That helps avoid single data points costing months or the appearance of a hung application.

I'll add more here after more data points complete running for 192M-fft-optimized core count on V20.1.1.

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File Type: pdf p1 run time scaling.pdf (39.1 KB, 3 views)

Last fiddled with by kriesel on 2021-11-18 at 18:40 Reason: update attachment which now includes gcd run time scaling
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