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Message boards : Proth Prime Search : Smaller FFT size, longer CPU time

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Bur
Volunteer tester

Joined: 25 Feb 20
Posts: 462
ID: 1241833
Credit: 279,927,511
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Message 145337 - Posted: 18 Nov 2020 | 18:28:53 UTC

While browsing PPS Mega tasks, I saw that some took 4100 s, some 5400 s. I assumed the latter had the larger FFT size and larger k, but not so.

Here are examples of each: 4100 s and 5400 s or the whole list here.

The difference seems to be the pass1 and pass2, in one case pass1 is larger, in the other pass2 is larger. And a is either 3 or 5.

What do these parameters mean and how do they influence the CPU time in such a way that smaller FFT size means longer CPU time? Especially since the tasks with shorter run times had the larger k and accordingly larger FFT.
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1281979 * 2^485014 + 1 is prime ... no further hits up to: n = 4,800,000

Eudy Silva

Joined: 26 Aug 17
Posts: 1540
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Message 145348 - Posted: 18 Nov 2020 | 20:25:28 UTC - in response to Message 145337.

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"Accidit in puncto, quod non contingit in anno."
Something that does not occur in a year may, perchance, happen in a moment.

Bur
Volunteer tester

Joined: 25 Feb 20
Posts: 462
ID: 1241833
Credit: 279,927,511
RAC: 549,978

Message 145388 - Posted: 19 Nov 2020 | 17:34:11 UTC - in response to Message 145348.

Ok, thanks I will continue in that thread.
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1281979 * 2^485014 + 1 is prime ... no further hits up to: n = 4,800,000

Message boards : Proth Prime Search : Smaller FFT size, longer CPU time