gpuOwL: an OpenCL program for Mersenne primality testing

[kriesel]

Originally Posted by preda

Can somebody please remind me what is the meaning of the last integer value ("0" below) in a PRP assignment such as:

PRP=700000F64405DAFE2EXXXXXXC85EEF72,1,2,91157779,-1,77,0

Do I understand correctly that when it's 0, it means "don't do any P-1"?
Then what does it mean when it's 1, 2, or what else can it be?

Roughly, number of primality tests that could be saved if a factor is found. https://www.mersenneforum.org/showpo...8&postcount=22

0 two or more primality tests have already been done, or sufficient P-1 factoring has already been done, make no effort on P-1 factoring
1 one primality test has already been done, make any P-1 effort that makes sense for that
2 no primality test or sufficient P-1 factoring done yet, make any P-1 effort that makes sense for that

In other usages, such as CUDAPm1, values higher than 2 up to 9 mean try harder to find a P-1 factor, with larger bounds. See also https://www.mersenneforum.org/showpo...4&postcount=17
If I recall correctly, inputs above 9 get effort capped equivalent to 9.

George's description of the optimization process is in the P-1 Factoring section of https://www.mersenne.org/various/math.php.
It's there to read in the source codes also.

Why do you ask; are you thinking of adding automatic bounds selection to gpuowl? If so, please go for the PrimeNet bounds so the P-1 task is retired.

The exponent in question had more than optimal TF applied and less than optimal P-1 bounds, and the net effect fell short of optimal factoring probability. https://www.mersenne.ca/exponent/91157779

[preda]

Thanks Ken for the explanation.
I'm thinking of adding "implicit preliminary P-1" for PRP assignments for exponents that didn't have any P-1.

So I obtain from PrimeNet one PRP assignment with one AID. I run both P-1 and PRP, now I have two results. With what AID should I submit the "implicit" P-1 result?

Originally Posted by kriesel

Roughly, number of primality tests that could be saved if a factor is found. https://www.mersenneforum.org/showpo...8&postcount=22

0 two or more primality tests have already been done, or sufficient P-1 factoring has already been done, make no effort on P-1 factoring
1 one primality test has already been done, make any P-1 effort that makes sense for that
2 no primality test or sufficient P-1 factoring done yet, make any P-1 effort that makes sense for that

In other usages, such as CUDAPm1, values higher than 2 up to 9 mean try harder to find a P-1 factor, with larger bounds. See also https://www.mersenneforum.org/showpo...4&postcount=17
If I recall correctly, inputs above 9 get effort capped equivalent to 9.

George's description of the optimization process is in the P-1 Factoring section of https://www.mersenne.org/various/math.php.
It's there to read in the source codes also.

Why do you ask; are you thinking of adding automatic bounds selection to gpuowl? If so, please go for the PrimeNet bounds so the P-1 task is retired.

The exponent in question had more than optimal TF applied and less than optimal P-1 bounds, and the net effect fell short of optimal factoring probability. https://www.mersenne.ca/exponent/91157779

[kriesel]

Originally Posted by preda

Thanks Ken for the explanation.
I'm thinking of adding "implicit preliminary P-1" for PRP assignments for exponents that didn't have any P-1.

So I obtain from PrimeNet one PRP assignment with one AID. I run both P-1 and PRP, now I have two results. With what AID should I submit the "implicit" P-1 result?

P-1 runs first. Assuming no factor is found: Submit the P-1 with AID 0. It will be accepted. It may generate some sort of warning as not the work type assigned for that user and exponent. It will leave the PRP assignment in place. Then when the PRP is completed, it gets reported with its AID and all's good.
If a factor is found, don't run the PRP, and try reporting the P-1 factor with its AID.

What do you mean by preliminary? Hopefully not a reduced-bounds P-1 run, which I've determined by test even if optimized for most factors per gpu hour, is a waste of resources. See https://www.mersenneforum.org/showpo...9&postcount=20

But not to worry: P-1 is covered on that one. https://www.mersenne.org/report_expo...1157779&full=1

[PhilF]

Originally Posted by preda

So I obtain from PrimeNet one PRP assignment with one AID. I run both P-1 and PRP, now I have two results. With what AID should I submit the "implicit" P-1 result?

I have submitted P-1 results twice now by pasting gpuowl's results.txt into Primenet's manual results submission page. One result had a factor, the other didn't. No AID. Both results were accepted without error and properly credited to my user account.

{"exponent":"103464293", "worktype":"PM1", "status":"F", "program":{"name":"gpuowl", "version":"v6.11-112-gf1b00d1"}, "timestamp":"2020-01-06 06:01:49 UTC", "user":"pfrakes", "computer":"i7-4790", "fft-length":5767168, "B1":50000, "B2":50000000, "factors":["2419588148340043449947153"]}

[preda]

Originally Posted by kriesel

What do you mean by preliminary? Hopefully not a reduced-bounds P-1 run

By "preliminary" I meant "subtask to be run before the main task".

About the bounds I propose an extremly simple heuristic for the defaults:
B1 = exponent / 100, rounded to a multiple of 100'000
B2 = 30 * B1

[kriesel]

Originally Posted by preda

By "preliminary" I meant "subtask to be run before the main task".

About the bounds I propose an extremly simple heuristic for the defaults:
B1 = exponent / 100, rounded to a multiple of 100'000
B2 = 30 * B1

That won't match either the GPUto72 or PrimeNet bounds goals, although it's probably close in effect to the PrimeNet figures. Sampling of both, and fits to them, can be seen at the attachment to https://www.mersenneforum.org/showpo...7&postcount=23.

[chalsall]

Originally Posted by kriesel

That won't match either the GPUto72 or PrimeNet bounds goals...

Ummm... Just to put on the table, GPU72 doesn't /have/ P-1 bounds. Our only dimension is TF "depth" (and range, of course).

Are you instead talking about the B1/B2 values chosen by Prime95/mprime based on the depth the candidate has already been TF'ed to?

Sorry... Juggling lots of different stuff, but your above confused me.

[kriesel]

Originally Posted by chalsall

Ummm... Just to put on the table, GPU72 doesn't /have/ P-1 bounds. Our only dimension is TF "depth" (and range, of course).

Are you instead talking about the B1/B2 values chosen by Prime95/mprime based on the depth the candidate has already been TF'ed to?

Sorry... Juggling lots of different stuff, but your above confused me.

What I was referring to is the B1 and B2 numbers listed in the Gputo72 row or PrimeNet row of any exponent entry at mersenne.ca. See for example https://www.mersenne.ca/exponent/200000033

[chalsall]

Originally Posted by kriesel

See for example https://www.mersenne.ca/exponent/200000033

Ah... Thank you. I truly was confused where all the references to GPU72 bounds was coming from. This now makes sense.

James: rational? I'm sure it's sane, knowing you...

[kriesel]

Originally Posted by chalsall

makes sense.

I try. And iterate.

[wfgarnett3]

Originally Posted by kriesel

This should have the -use CARRY32 default that Preda described above. I've only gone as far as running -h on it so far. Build again had the usual shower of warnings.

Just when I think we're at diminishing returns or at the end of optimizations, George provides another pleasant surprise.

I downloaded this gpuowl-v6.11-112-gf1b00d1.7z windows exe file that kriesel posted.

However it seems to have CPU usage (and I checked Task Manager to verify).

Whenever I have it running on the GPU and Prime95 on the CPU the iteration time on Prime95 slows down. Once I stop gpuowl Prime95 goes back to its normal iteration time, but as soon as I restart gpuowl Prime95 slows back down.

This is my first real usage of gpuowl (I am "double-checking" a PRP number just to test the software out).

This never happened when I double-checked LL for CudaLucas - CudaLucas (or mfaktc for TF) running on the GPU never affected Prime95 running simultanosly on the CPU.

Can someone tell me why this happens?

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