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Old 2021-01-24, 19:20   #1
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Mar 2017
US midwest

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(Most content in this post will come and go and be of temporary interest at best.)

If performing first primality tests, use PRP with GEC and proof generation. NO LL for first tests! Or for DC either.

Please switch for first tests, to PRP testing, with the excellent Gerbicz Error Check, and VDF based verification of correct completion ("proof"), wherever practical, instead of doing LL first tests. Cease beginning LL first primality tests. All new first primality tests should be PRP type, with proof generation whenever possible. PRP/GEC/proof/Cert is much more reliable, and effectively twice as fast, since it essentially eliminates the typical 2% LL error rate leading to occasional triple checks or further, and reduces verification to typically under 1% of what an LL DC requires. If the choices are between Gpuowl PRP or CUDALucas LL, the savings are even more dramatic, nearly 4:1. PRP with proof generation also provides much faster indication of system reliability (typically hours), than does LL. (Typically years, 8.2 in that example, for an LL DC to occur; examples over 9 years also exist:

Since the reliability advantage of PRP/GEC over LL also applies to double checking, most LL first tests will never have LLDC run. They will instead be verified composite more reliably and more quickly by a first time PRP/GEC/proof and cert. So in the usual >999999 ppm case of a composite Mersenne number, an LL first primality test is a complete waste of time and computing resources. (An LL DC on an LL first test is a lesser waste of time, and less reliable than PRP.)

Mprime/prime95 (~v30.3 or higher), and GpuOwl (~v6.11-316 and later) are available in proof-capable forms. Mlucas proof capability is planned for V20 (after P-1 is added). (Lucas-Lehmer tests will still be used if/when PRP returns a probable prime indication for a suspected new Mersenne prime discovery, to confirm by multiple independent tests by separate hardware, software, and participants. The person reporting a PRP probable prime indication from a first test would still be regarded as the discoverer.)
In a recent sampling ~2021-01-24 of over 130 primality testing assignments in 101-102M, 38% were LL, 62% PRP. That LL frequency is much too high.
As of 2021-01-27 1540 UTC in 101-102M primality testing of 273 active assignments, 57 LL, 21%, better. For 101M-103M as of 2021-03-28 ~2010 UTC, 23 LL of 132, 17%. Let's keep moving away from inefficient LL first tests, that are very slowly double-checked, toward complete conversion to the far more reliable and efficient PRP/GEC/proof/Cert that also provides very rapid verification. Drive LL percentage toward 0%.
GPUs that can run either CUDALucas or gpuowl should run PRP/GEC/proof on gpuowl as primality tests. (That would include all Google Colab gpu models. The Google Drive free space is sufficient.)

Please run assignments promptly or visit to turn them back in so someone else can run them.

(This is not a discussion thread. Please do not post in this thread. Use PM or a discussion thread. Most content in this thread will be temporary.)
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Last fiddled with by kriesel on 2021-04-10 at 17:12 Reason: updated ll/prp status
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