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Message boards : Number crunching : LLR for GPU

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Profile Kevin Erickson
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Joined: 12 Aug 05
Posts: 30
ID: 227
Credit: 69,355,276
RAC: 40,516
321 LLR Silver: Earned 100,000 credits (134,537)Cullen LLR Silver: Earned 100,000 credits (167,641)Generalized Cullen/Woodall LLR Silver: Earned 100,000 credits (200,326)PPS LLR Amethyst: Earned 1,000,000 credits (1,099,287)PSP LLR Silver: Earned 100,000 credits (358,370)SoB LLR Amethyst: Earned 1,000,000 credits (1,326,630)SR5 LLR Gold: Earned 500,000 credits (761,994)SGS LLR Silver: Earned 100,000 credits (171,388)TPS LLR (retired) Silver: Earned 100,000 credits (252,211)TRP LLR Gold: Earned 500,000 credits (531,632)Woodall LLR Gold: Earned 500,000 credits (520,462)PPS Sieve Emerald: Earned 50,000,000 credits (54,680,991)Sierpinski (ESP/PSP/SoB) Sieve (suspended) Bronze: Earned 10,000 credits (24,363)AP 26/27 Turquoise: Earned 5,000,000 credits (5,222,964)GFN Ruby: Earned 2,000,000 credits (3,888,985)
Message 83568 - Posted: 27 Feb 2015 | 3:28:28 UTC

Hi all,

Is there a reason why there are no GPU options for LLR tasks?

SOB or 321 could fly on my gtx970!
____________

HonzaProject donor
Volunteer moderator
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Project scientist
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Joined: 15 Aug 05
Posts: 1875
ID: 352
Credit: 2,992,546,861
RAC: 1,200,357
Discovered 7 mega primesEliminated 4 conjecture "k"sFound 2 primes in the 2018 Tour de PrimesFound 1 prime in the 2018 Tour de Primes Mountain Stage2019 Tour de Primes largest primeFound 4 primes in the 2019 Tour de PrimesFound 1 mega prime in the 2019 Tour de PrimesFound 1 prime in the 2019 Tour de Primes Mountain StageFound 1 prime in the 2020 Tour de Primes321 LLR Emerald: Earned 50,000,000 credits (62,020,570)Cullen LLR Emerald: Earned 50,000,000 credits (50,296,190)ESP LLR Emerald: Earned 50,000,000 credits (50,853,190)Generalized Cullen/Woodall LLR Emerald: Earned 50,000,000 credits (50,309,119)PPS LLR Double Bronze: Earned 100,000,000 credits (117,948,698)PSP LLR Emerald: Earned 50,000,000 credits (50,563,867)SoB LLR Emerald: Earned 50,000,000 credits (90,938,749)SR5 LLR Double Bronze: Earned 100,000,000 credits (101,883,529)SGS LLR Emerald: Earned 50,000,000 credits (53,154,727)TPS LLR (retired) Bronze: Earned 10,000 credits (43,033)TRP LLR Double Bronze: Earned 100,000,000 credits (100,124,194)Woodall LLR Emerald: Earned 50,000,000 credits (50,956,094)321 Sieve Double Bronze: Earned 100,000,000 credits (115,913,077)Cullen/Woodall Sieve (suspended) Ruby: Earned 2,000,000 credits (4,142,109)Generalized Cullen/Woodall Sieve (suspended) Emerald: Earned 50,000,000 credits (50,504,945)PPS Sieve Double Gold: Earned 500,000,000 credits (513,057,580)Sierpinski (ESP/PSP/SoB) Sieve (suspended) Sapphire: Earned 20,000,000 credits (20,288,222)TRP Sieve (suspended) Sapphire: Earned 20,000,000 credits (20,149,354)AP 26/27 Double Silver: Earned 200,000,000 credits (232,724,773)GFN Double Gold: Earned 500,000,000 credits (721,432,847)PSA Double Gold: Earned 500,000,000 credits (535,232,795)
Message 83573 - Posted: 27 Feb 2015 | 7:27:17 UTC
Last modified: 27 Feb 2015 | 7:32:20 UTC

Yes, there is - it would not fly.

It was found to be not efficient enough - it is not much faster like GFN or sieving (GPU vs CPU) and uses a lot of CPU as well.

While GPU is limited to a single task, CPU can do 4, 6, 8 or even more depending on number of cores - with less power usage.

EDIT: found it, see Operational LLR-GPU application already running here?. There was more on discussion about LLR / GPU back in 2011 and later on PrimeGrid threads.
____________
My stats
Badge score: 1*1 + 5*1 + 8*3 + 9*11 + 10*1 + 11*1 + 12*3 = 186

Profile Kevin Erickson
Send message
Joined: 12 Aug 05
Posts: 30
ID: 227
Credit: 69,355,276
RAC: 40,516
321 LLR Silver: Earned 100,000 credits (134,537)Cullen LLR Silver: Earned 100,000 credits (167,641)Generalized Cullen/Woodall LLR Silver: Earned 100,000 credits (200,326)PPS LLR Amethyst: Earned 1,000,000 credits (1,099,287)PSP LLR Silver: Earned 100,000 credits (358,370)SoB LLR Amethyst: Earned 1,000,000 credits (1,326,630)SR5 LLR Gold: Earned 500,000 credits (761,994)SGS LLR Silver: Earned 100,000 credits (171,388)TPS LLR (retired) Silver: Earned 100,000 credits (252,211)TRP LLR Gold: Earned 500,000 credits (531,632)Woodall LLR Gold: Earned 500,000 credits (520,462)PPS Sieve Emerald: Earned 50,000,000 credits (54,680,991)Sierpinski (ESP/PSP/SoB) Sieve (suspended) Bronze: Earned 10,000 credits (24,363)AP 26/27 Turquoise: Earned 5,000,000 credits (5,222,964)GFN Ruby: Earned 2,000,000 credits (3,888,985)
Message 83574 - Posted: 27 Feb 2015 | 11:25:53 UTC - in response to Message 83573.

Thanks Honza,

I guess I don't understand the architecture of GPUs very well.
I was thinking there could be one llr per cuda core or use ever cuda core to test one llr in a couple of seconds.

P.S. Heh, not too many people have a lower ID number than you ;)
____________

HonzaProject donor
Volunteer moderator
Volunteer tester
Project scientist
Send message
Joined: 15 Aug 05
Posts: 1875
ID: 352
Credit: 2,992,546,861
RAC: 1,200,357
Discovered 7 mega primesEliminated 4 conjecture "k"sFound 2 primes in the 2018 Tour de PrimesFound 1 prime in the 2018 Tour de Primes Mountain Stage2019 Tour de Primes largest primeFound 4 primes in the 2019 Tour de PrimesFound 1 mega prime in the 2019 Tour de PrimesFound 1 prime in the 2019 Tour de Primes Mountain StageFound 1 prime in the 2020 Tour de Primes321 LLR Emerald: Earned 50,000,000 credits (62,020,570)Cullen LLR Emerald: Earned 50,000,000 credits (50,296,190)ESP LLR Emerald: Earned 50,000,000 credits (50,853,190)Generalized Cullen/Woodall LLR Emerald: Earned 50,000,000 credits (50,309,119)PPS LLR Double Bronze: Earned 100,000,000 credits (117,948,698)PSP LLR Emerald: Earned 50,000,000 credits (50,563,867)SoB LLR Emerald: Earned 50,000,000 credits (90,938,749)SR5 LLR Double Bronze: Earned 100,000,000 credits (101,883,529)SGS LLR Emerald: Earned 50,000,000 credits (53,154,727)TPS LLR (retired) Bronze: Earned 10,000 credits (43,033)TRP LLR Double Bronze: Earned 100,000,000 credits (100,124,194)Woodall LLR Emerald: Earned 50,000,000 credits (50,956,094)321 Sieve Double Bronze: Earned 100,000,000 credits (115,913,077)Cullen/Woodall Sieve (suspended) Ruby: Earned 2,000,000 credits (4,142,109)Generalized Cullen/Woodall Sieve (suspended) Emerald: Earned 50,000,000 credits (50,504,945)PPS Sieve Double Gold: Earned 500,000,000 credits (513,057,580)Sierpinski (ESP/PSP/SoB) Sieve (suspended) Sapphire: Earned 20,000,000 credits (20,288,222)TRP Sieve (suspended) Sapphire: Earned 20,000,000 credits (20,149,354)AP 26/27 Double Silver: Earned 200,000,000 credits (232,724,773)GFN Double Gold: Earned 500,000,000 credits (721,432,847)PSA Double Gold: Earned 500,000,000 credits (535,232,795)
Message 83575 - Posted: 27 Feb 2015 | 12:30:37 UTC - in response to Message 83574.

I guess I don't understand the architecture of GPUs very well.
I was thinking there could be one llr per cuda core or use ever cuda core to test one llr in a couple of seconds.

P.S. Heh, not too many people have a lower ID number than you ;)

Well, neither am I expert on GPU architecture.

Consider this:
My GTX580 from 2010 has 512 cores, GTX 780 Ti has 2880. LLR takes ~12MB (for a megaprime), and ~40MB for largest known PG's 321 prime. This would be 5-20GB RAM (low estimate) or 115GB RAM for GTX780Ti.
There is also GPU memory usage and GPUs are more memory limited (can't add 32 of 16GB memory sticks likes server).
Firing up 512 or 2880 instances of LLR would be disk intensive, saving checkpoints etc.

Even if we manage to do all this, CPU would not be able to feed hundreds of LLR/GPU instances, memory bandwith would need to be hundred times wider etc.

We would need to go parallel with single LLR test. Easy to say, hard to do. Or at least easier to do with sieving, not LLR.

At last (and not least), "It's surprisingly easy to make a very slow GPU program...not sure there's a way to convert it into a fast GPU program"

Perhaps there will be different approach developed or new hardware possibilities in future. Until then, were are good with CPU - latest FMA is doing very well.
____________
My stats
Badge score: 1*1 + 5*1 + 8*3 + 9*11 + 10*1 + 11*1 + 12*3 = 186

Message boards : Number crunching : LLR for GPU

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