Maximum Prime Size for Large Prime Workunits

Message boards : Number crunching : Maximum Prime Size for Large Prime Workunits

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Kellen

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Message 1136 - Posted: 19 May 2019, 3:30:31 UTC
Last modified: 19 May 2019, 3:35:56 UTC

Hi Sergei,

Just out of curiosity; what will the largest prime number be for these current large prime workunits? We are now at approximately 1.3E18. Will we go all the way to 1.0E20, or will the /lpr units stop at some lower value?

Thank you,
Kellen

Edit: Corrected "10E20" to "1.0E20".
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Sergei Chernykh
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Message 1137 - Posted: 19 May 2019, 7:43:43 UTC - in response to Message 1136.  

The largest prime will be 5E18 (1E20 / 20) because numbers of the form N*P where N < 20 and P is prime can't be amicable.
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Kellen

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Message 1138 - Posted: 19 May 2019, 11:27:43 UTC - in response to Message 1137.  

Hi Sergei,

Thank you very much for this information. I became curious when noticing the very large drop in the "/task_size" parameter when we passed 1.25E18 and the corresponding reduction in run times, despite the fact that each workunit now moves through a range of ~4.38E12 instead of the ~3.58E12 range prior to passing 1.25E18.

On a side note, this increased range and the fact that we need only reach 5E18 means that we now have less than a million workunits left! [(5E18-1.31E18)/(4.38E12)=842,466] I anticipate another large drop in the "/task_size" parameter at 2.5E18 (and maybe also one at 1.5625E18, 1.6667E18 and a few other spots, although I'm not as confident about those values being related to a large task size decrease), so this number of workunits is likely much smaller and could be closer to 500,000.

With the decreased run times (on CPU) and the small number of workunits left, we may progress through the final 10% quite quickly, compared to recent progress speed.

Regards,
Kellen
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Kellen

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Message 1145 - Posted: 24 May 2019, 0:06:09 UTC - in response to Message 1138.  

Hi All,

The tested range per workunit is now 5.84E12, so the progress towards 5E18 has once again accelerated. The increase occurred at 1.42587E18 and there are now approximately 600,000 workunits left between our present leading edge Large Prime task and 5E18 assuming no further range improvements.

To follow up with the predictions in my previous post; I am no longer expecting another speedup at 1.5625E18, but the one at 1.6667E18 is still very likely, so we will probably see further improvements in the range for these Large Prime workunits.

On another note, to anyone who stopped crunching Amicable Numbers on CPU due to the very long run times of the CPU tasks; this issue is a thing of the distant past. The CPU application is about as efficient as it has ever been now that we are in this very high range.

Best of luck to all!

Regards,
Kellen
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Sergei Chernykh
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Message 1146 - Posted: 24 May 2019, 6:42:42 UTC - in response to Message 1145.  

I've just checked "unsent WUs" directory on the server: there are 705,478 WU left right now.
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Kellen

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Message 1147 - Posted: 24 May 2019, 11:23:45 UTC - in response to Message 1146.  

Hi Sergei,

Many thanks for this information! Looking forward to getting into those early 10^21 ranges with lots of amicable pairs, so it is nice to have the remaining 10^20 work quantified like this.

Thank you,
Kellen
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Chara34122

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Message 1161 - Posted: 10 Jun 2019, 8:22:23 UTC

What factor is the largest in amicable pairs up the 2^64?
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Speedy

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Message 1175 - Posted: 20 Jun 2019, 21:45:37 UTC

It's great to see the speed up in CPU time. I am deviating slightly with this question but feel it still fits in this thread. Is the server status page still accurate? It says we will be finished in October 91.4824% average of 3.88 hours. I thought with faster work units this would of been August or September maybe not?
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Kellen

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Message 1176 - Posted: 20 Jun 2019, 23:20:44 UTC - in response to Message 1175.  

Hi Speedy,

The server page is accurate with the percentage complete, but the completion date is probably closer to your estimate. My guess for completion date, assuming participation remains the same, is sometime on the week of September 2, 2019. :)

Regards,
Kellen
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Message boards : Number crunching : Maximum Prime Size for Large Prime Workunits


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