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Message boards : Generalized Fermat Prime Search : GFN-17-MEGA at CPU B-Limit

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Profile Michael GoetzProject donor
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Joined: 21 Jan 10
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The "Shut up already!" badge:  This loud mouth has mansplained on the forums over 10 thousand times!  Sheesh!!!Discovered the World's First GFN-19 prime!!!Discovered 1 mega primeFound 1 prime in the 2018 Tour de PrimesFound 1 prime in the 2019 Tour de PrimesFound 1 prime in the 2020 Tour de Primes321 LLR Ruby: Earned 2,000,000 credits (2,822,730)Cullen LLR Ruby: Earned 2,000,000 credits (2,005,249)ESP LLR Turquoise: Earned 5,000,000 credits (5,009,577)Generalized Cullen/Woodall LLR Ruby: Earned 2,000,000 credits (2,145,754)PPS LLR Jade: Earned 10,000,000 credits (12,843,762)PSP LLR Turquoise: Earned 5,000,000 credits (5,197,957)SoB LLR Sapphire: Earned 20,000,000 credits (34,291,181)SR5 LLR Jade: Earned 10,000,000 credits (10,004,590)SGS LLR Ruby: Earned 2,000,000 credits (2,276,011)TRP LLR Ruby: Earned 2,000,000 credits (2,737,347)Woodall LLR Ruby: Earned 2,000,000 credits (2,195,123)321 Sieve Turquoise: Earned 5,000,000 credits (9,403,130)Cullen/Woodall Sieve (suspended) Ruby: Earned 2,000,000 credits (4,170,256)Generalized Cullen/Woodall Sieve (suspended) Turquoise: Earned 5,000,000 credits (5,059,304)PPS Sieve Sapphire: Earned 20,000,000 credits (20,114,159)Sierpinski (ESP/PSP/SoB) Sieve (suspended) Amethyst: Earned 1,000,000 credits (1,035,522)TRP Sieve (suspended) Ruby: Earned 2,000,000 credits (2,051,121)AP 26/27 Jade: Earned 10,000,000 credits (10,114,260)GFN Emerald: Earned 50,000,000 credits (72,383,585)PSA Jade: Earned 10,000,000 credits (12,404,447)
Message 128932 - Posted: 22 Apr 2019 | 13:06:10 UTC

We appear to have reached the b-limit for the x87 transform on 17-MEGA. I've disabled the GPU apps for 17-MEGA, and you will no longer be able to get CPU tasks for 17-MEGA.

If you have 17-MEGA CPU tasks in progress, you might want to consider aborting them if they're near the beginning. If they're near the end I'd probably let them complete. It's impossible to predict which tasks will succeed and which will fail.

More details can be found here: https://www.primegrid.com/forum_thread.php?id=8557, although discussion should occur in this thread.
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Discovered 1 mega primeFound 1 prime in the 2018 Tour de PrimesFound 1 prime in the 2019 Tour de PrimesFound 1 prime in the 2020 Tour de Primes321 LLR Turquoise: Earned 5,000,000 credits (9,919,609)Cullen LLR Turquoise: Earned 5,000,000 credits (9,934,320)ESP LLR Turquoise: Earned 5,000,000 credits (9,909,084)Generalized Cullen/Woodall LLR Turquoise: Earned 5,000,000 credits (9,897,915)PPS LLR Jade: Earned 10,000,000 credits (11,055,307)PSP LLR Turquoise: Earned 5,000,000 credits (9,676,438)SoB LLR Turquoise: Earned 5,000,000 credits (5,824,522)SR5 LLR Turquoise: Earned 5,000,000 credits (9,904,596)SGS LLR Turquoise: Earned 5,000,000 credits (6,074,879)TRP LLR Turquoise: Earned 5,000,000 credits (9,911,706)Woodall LLR Turquoise: Earned 5,000,000 credits (6,196,794)321 Sieve Sapphire: Earned 20,000,000 credits (20,004,228)Generalized Cullen/Woodall Sieve (suspended) Sapphire: Earned 20,000,000 credits (20,047,667)PPS Sieve Sapphire: Earned 20,000,000 credits (20,866,490)Sierpinski (ESP/PSP/SoB) Sieve (suspended) Sapphire: Earned 20,000,000 credits (20,043,271)TRP Sieve (suspended) Sapphire: Earned 20,000,000 credits (20,015,177)AP 26/27 Sapphire: Earned 20,000,000 credits (20,045,194)GFN Emerald: Earned 50,000,000 credits (52,210,295)PSA Double Silver: Earned 200,000,000 credits (200,301,443)
Message 128934 - Posted: 22 Apr 2019 | 13:19:57 UTC - in response to Message 128932.


We're still theoretically about 6 million away from the B limit, but the limit is fuzzy and some candidates will produce much higher (or lower) error values than surrounding candidates.

There is no fixed limit which could be calculated easily. B/MaxErr graph look like set of triangles (or like a triangle wave where triangles have same amplitude, but "DC offset" rising slowly as B grows). First, only few tasks (top corners of triangles) will touch the limit line, but almost all of tasks still could be completed. Over time, as B and "DC offset" grows, more and more tasks will be above limit, and error will eventually be noticed by "limit test" or something like this.

Profile Michael GoetzProject donor
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The "Shut up already!" badge:  This loud mouth has mansplained on the forums over 10 thousand times!  Sheesh!!!Discovered the World's First GFN-19 prime!!!Discovered 1 mega primeFound 1 prime in the 2018 Tour de PrimesFound 1 prime in the 2019 Tour de PrimesFound 1 prime in the 2020 Tour de Primes321 LLR Ruby: Earned 2,000,000 credits (2,822,730)Cullen LLR Ruby: Earned 2,000,000 credits (2,005,249)ESP LLR Turquoise: Earned 5,000,000 credits (5,009,577)Generalized Cullen/Woodall LLR Ruby: Earned 2,000,000 credits (2,145,754)PPS LLR Jade: Earned 10,000,000 credits (12,843,762)PSP LLR Turquoise: Earned 5,000,000 credits (5,197,957)SoB LLR Sapphire: Earned 20,000,000 credits (34,291,181)SR5 LLR Jade: Earned 10,000,000 credits (10,004,590)SGS LLR Ruby: Earned 2,000,000 credits (2,276,011)TRP LLR Ruby: Earned 2,000,000 credits (2,737,347)Woodall LLR Ruby: Earned 2,000,000 credits (2,195,123)321 Sieve Turquoise: Earned 5,000,000 credits (9,403,130)Cullen/Woodall Sieve (suspended) Ruby: Earned 2,000,000 credits (4,170,256)Generalized Cullen/Woodall Sieve (suspended) Turquoise: Earned 5,000,000 credits (5,059,304)PPS Sieve Sapphire: Earned 20,000,000 credits (20,114,159)Sierpinski (ESP/PSP/SoB) Sieve (suspended) Amethyst: Earned 1,000,000 credits (1,035,522)TRP Sieve (suspended) Ruby: Earned 2,000,000 credits (2,051,121)AP 26/27 Jade: Earned 10,000,000 credits (10,114,260)GFN Emerald: Earned 50,000,000 credits (72,383,585)PSA Jade: Earned 10,000,000 credits (12,404,447)
Message 128935 - Posted: 22 Apr 2019 | 13:33:06 UTC

Besides the original error, we've now seen the same task error out on a Kaby Lake, an Ivy Bridge, and the same model Sandy Bridge as the original. It's safe to say we've hit the limit.


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Profile mikey
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Discovered 1 mega prime321 LLR Ruby: Earned 2,000,000 credits (2,038,739)Cullen LLR Amethyst: Earned 1,000,000 credits (1,165,737)ESP LLR Amethyst: Earned 1,000,000 credits (1,032,929)Generalized Cullen/Woodall LLR Amethyst: Earned 1,000,000 credits (1,046,510)PPS LLR Turquoise: Earned 5,000,000 credits (5,090,575)PSP LLR Amethyst: Earned 1,000,000 credits (1,325,581)SoB LLR Amethyst: Earned 1,000,000 credits (1,043,824)SR5 LLR Ruby: Earned 2,000,000 credits (2,053,250)SGS LLR Turquoise: Earned 5,000,000 credits (5,095,282)TRP LLR Amethyst: Earned 1,000,000 credits (1,937,770)Woodall LLR Amethyst: Earned 1,000,000 credits (1,088,488)321 Sieve Ruby: Earned 2,000,000 credits (3,254,140)Cullen/Woodall Sieve (suspended) Gold: Earned 500,000 credits (944,431)Generalized Cullen/Woodall Sieve (suspended) Sapphire: Earned 20,000,000 credits (20,813,253)PPS Sieve Double Silver: Earned 200,000,000 credits (339,142,907)Sierpinski (ESP/PSP/SoB) Sieve (suspended) Ruby: Earned 2,000,000 credits (2,446,797)AP 26/27 Sapphire: Earned 20,000,000 credits (33,140,471)GFN Sapphire: Earned 20,000,000 credits (27,517,414)PSA Sapphire: Earned 20,000,000 credits (20,457,430)
Message 128938 - Posted: 22 Apr 2019 | 13:55:22 UTC - in response to Message 128932.

We appear to have reached the b-limit for the x87 transform on 17-MEGA. I've disabled the GPU apps for 17-MEGA, and you will no longer be able to get CPU tasks for 17-MEGA.

If you have 17-MEGA CPU tasks in progress, you might want to consider aborting them if they're near the beginning. If they're near the end I'd probably let them complete. It's impossible to predict which tasks will succeed and which will fail.

More details can be found here: https://www.primegrid.com/forum_thread.php?id=8557, although discussion should occur in this thread.


So are you going to remove the cpu checkbox on the Primegrid project preferences page at some point?

Generalized Fermat Prime Search n=17, b>=42,597,774 (GFN-17-Mega or Genefer 131072 Mega)
b131072+1 (or b217+1), b>=42,597,774

Deadline: 4 days (up to 30 days)

Recent average CPU time: 12:05:54
Recent average GPU time: 0:24:07

CPU

OpenCL1,2,7,10,11
OpenCL1,6,7

Profile Michael GoetzProject donor
Honorary cruncher
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Joined: 21 Jan 10
Posts: 13213
ID: 53948
Credit: 218,265,066
RAC: 12,106
The "Shut up already!" badge:  This loud mouth has mansplained on the forums over 10 thousand times!  Sheesh!!!Discovered the World's First GFN-19 prime!!!Discovered 1 mega primeFound 1 prime in the 2018 Tour de PrimesFound 1 prime in the 2019 Tour de PrimesFound 1 prime in the 2020 Tour de Primes321 LLR Ruby: Earned 2,000,000 credits (2,822,730)Cullen LLR Ruby: Earned 2,000,000 credits (2,005,249)ESP LLR Turquoise: Earned 5,000,000 credits (5,009,577)Generalized Cullen/Woodall LLR Ruby: Earned 2,000,000 credits (2,145,754)PPS LLR Jade: Earned 10,000,000 credits (12,843,762)PSP LLR Turquoise: Earned 5,000,000 credits (5,197,957)SoB LLR Sapphire: Earned 20,000,000 credits (34,291,181)SR5 LLR Jade: Earned 10,000,000 credits (10,004,590)SGS LLR Ruby: Earned 2,000,000 credits (2,276,011)TRP LLR Ruby: Earned 2,000,000 credits (2,737,347)Woodall LLR Ruby: Earned 2,000,000 credits (2,195,123)321 Sieve Turquoise: Earned 5,000,000 credits (9,403,130)Cullen/Woodall Sieve (suspended) Ruby: Earned 2,000,000 credits (4,170,256)Generalized Cullen/Woodall Sieve (suspended) Turquoise: Earned 5,000,000 credits (5,059,304)PPS Sieve Sapphire: Earned 20,000,000 credits (20,114,159)Sierpinski (ESP/PSP/SoB) Sieve (suspended) Amethyst: Earned 1,000,000 credits (1,035,522)TRP Sieve (suspended) Ruby: Earned 2,000,000 credits (2,051,121)AP 26/27 Jade: Earned 10,000,000 credits (10,114,260)GFN Emerald: Earned 50,000,000 credits (72,383,585)PSA Jade: Earned 10,000,000 credits (12,404,447)
Message 128939 - Posted: 22 Apr 2019 | 14:03:39 UTC - in response to Message 128938.

So are you going to remove the cpu checkbox on the Primegrid project preferences page at some point?


Yes, but that's not a trivial change. It will have to wait until later today.
____________
My lucky number is 75898524288+1
(I am NOT an administrator anymore, so please don't PM me with questions. I can't help.)

Message boards : Generalized Fermat Prime Search : GFN-17-MEGA at CPU B-Limit

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