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drummers-lowrise
1) Message boards : Number crunching : Badges III (Message 149542)
Posted 31 days ago by GDB
My 5th Double Bronze.
2) Message boards : Number crunching : 2021 Primegrid Mega Prime finders by quantity found. (Message 149231)
Posted 41 days ago by GDB
Updated for GDB Congrats!!!

Total Mega Primes found to date on PrimeGrid 679

Total Mega Primes found this year on PrimeGrid 99


First Post Updated



My 1st Mega, and 18 months since my last prime find.
3) Message boards : Number crunching : Badges III (Message 148933)
Posted 56 days ago by GDB
My ninth jade.
4) Message boards : Number crunching : PrimeGrid Years (Message 148671)
Posted 63 days ago by GDB
9.25 years
5) Message boards : Number crunching : Badges III (Message 147693)
Posted 89 days ago by GDB
My 5th Emerald badge.
6) Message boards : Generalized Fermat Prime Search : Guessing the future of GFN-22 and DYFL (Message 147371)
Posted 104 days ago by GDB
Now I'm asking once again: what are runtimes of real GFN-22/DYFL tasks on your GPUs? When I'll know runtimes, I can calculate how efficient sieve will be and how far it should go to stay efficient in your setup.

The last line of his latest post may mean that the Genefer runtime is about a day. /JeppeSN


Need to know *which* GFN you're talking about. DYFL uses a slower transform than GFN-22, so it takes about 25% longer to run.


So, my question is do I run GFN-22 and/or DYFL for each card?
7) Message boards : Generalized Fermat Prime Search : Guessing the future of GFN-22 and DYFL (Message 147368)
Posted 104 days ago by GDB
To get specific current timing for each GPU, I'll need to run small manual GFN22 sieve on each. Do you want the time for a GFN22 and/or DYFL for each card?
8) Message boards : Generalized Fermat Prime Search : Guessing the future of GFN-22 and DYFL (Message 147361)
Posted 104 days ago by GDB
What is sieving speed of your GPU (P/day) ?


With my 2 1080s and 2060, I was doing 800 P per day for n=22 manual sieving.

At a removal rate of 1.5 candidates per P, I was removing 1200 candidates per day.

OK. You're sieving 800 P/day. You see that lot of factors were found.

Question #1. How many of these factors are really removing a candidate (i.e. candidate wasn't removed earlier by smaller factors)?

Yves has formulas for everything related to GFN. He also has a formula to calculate number of candidates left at given sieving depth and range. Current GFN-22 sieving depth is 1100000P and range is 2G. How many candidates will be removed between 1100000P and 1100000+800P ? Put both depths to formula and find a difference. The answer is (you have to trust my word) 6055.

Question #2. How many of these 6055 factors are useful to us?

There is a problem with candidates located too far from our current position in search. Sieving can find these factors "for free", up to 2G, but why - if we'll need, for example, 100 years to reach this range?

So we use 5 years prediction for "usable" range, based on progress for few last years. And the sad truth is that prediction (advance of 'b') for GFN-22 is only 245000!

You removed 6055 from 2G range. How may candidates are within 245K range?

6055 * 245000 / 2000000000 = 0,7417375

Multiply by two due to DC tasks. So, your whole day of sieving on 3 GPUs saved only 1,5 useful (within next 5 years) tasks.

What is duration of real tasks on these GPUs?


If you go to manual sieving, and click on "show stats", it shows stats for all GFN manual sieving. Go to GFN n=22, and click "+" to expand all GFN n=22 stats. Go all of the way to the end of n=22 stats.
User walli shows up last doing 600P jobs, and removes from the sieve about 900 candidates for each job. That's 1.5 candidates removed per P.

It also shows factors found as about 3.8. That means 1.5 candidates removed per P divided by 3.8 factors found = about 40% of factors found result in a candidate removal.
Obviously as you sieve more, the % of factors resulting in a candidate removal will slowly decrease.

As to your question #1, from actual sieve job stats near your range, 800P at 1.5 candidates removed per P = 1200 candidates removed per day, not your 6055.

As to your question #2, your usable range of 245,000 is way too small. Forget about DYFL?
DYFL is already to 925,000 for GFN22. And if a World record GIMP is found, DYFL probably will be bumped. So a much more reasonable 5 year range is 2,000,000.

So, 1200 * 2,000,000 / 2,000,000,000 = 1.2 * 2 (for DC tasks) = 2.4 useful candidates removed per day via manual sieving. Along with the equivalent of 2,400 other candidates removed from sieve.

It seems such a waste of GPU resources to me to remove 1 GFN22 candidate per day instead of 1200 via manual sieving.


9) Message boards : Problems and Help : Can't figure out why CPU isn't being used 100% (Message 147350)
Posted 104 days ago by GDB
I recommend app "Core Temp" for tracking your CPU temps.
10) Message boards : Generalized Fermat Prime Search : Guessing the future of GFN-22 and DYFL (Message 147344)
Posted 104 days ago by GDB
What is sieving speed of your GPU (P/day) ?


With my 2 1080s and 2060, I was doing 800 P per day for n=22 manual sieving.

At a removal rate of 1.5 candidates per P, I was removing 1200 candidates per day.


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