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Old 2010-03-03, 18:14   #12
joblack
 
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Quote:
Originally Posted by lycorn View Post
Unless you are really keen to find a prime, I would reccommend the setting proposed by garo on post #3: DC/DC/DC/P-1. These are the types of work GIMPS is in most need at the moment.
I am assuming your machine has an amount of memory suitable for P-1 work. If that is not the case, the fourth worker could either do DC, or, if you start noticing a slowdown due to memory access congestion, Trial Factoring.
I don't see the 'fuzz' / problem with the P-1. If nobody else has done it before don't you just do it at the beginning of your LL test?
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Old 2010-03-03, 18:22   #13
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Quote:
Originally Posted by joblack View Post
I don't see the 'fuzz' / problem with the P-1. If nobody else has done it before don't you just do it at the beginning of your LL test?
Yes, but how often will machines that are mainly used for LL allow enough memory to have a really worthwhile P-1 test? I don't really know, but I'm sure more factors are found when you get computers more dedicated towards P-1 to do that part.
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Old 2010-03-04, 08:59   #14
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True. Machines that are dedicated to LL testing are very often left with the default Prime95 memory allocation, which is substantially lower than the values allocated by somebody dedicating a given machine to P-1 work. Therefore, the probability of finding a factor is higher if you have "specialized" P-1 factor hunters.
Note as well that P-1 is performed on a given exponent before the final level of TF. If P-1 is done before the front wave of LL reaches the exponent, the TF will also be done by somebody working specifically on TF, so when the exponent is finally handed over to the LL tester, nothing else is left to do, and the tester can immediately proceed to the type of work he´s actually willing to do.
In the database one can find many examples of exponents LL tested, but with only Stage 1 performed, or even no P-1 test at all; these correspond to people allocating small amounts of memory to P-1 or even skipping the test altogether. Some of these tests (and the DC that will have to follow) could have been avoided had P-1 been properly done.
To summarize: the advantages of having P-1 as a separate assignment type are: a higher chance of finding factors, and to allow people to work just on what they really want, therefore raising their level of motivation.
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Old 2010-03-05, 04:10   #15
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mine are DC/P-1/LL/LL
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Old 2010-03-08, 22:41   #16
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2 machines - dc/dc/dc/p-1 and dc/p-1

I'd do more p-1 as I have plenty of ram - but the version of prime I'm running, mprime ignores the 'mem per thread' option int he config files. Not sure if this is fixed in later versions.

-- Craig
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Old 2010-03-09, 18:50   #17
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The current version (25.11) of Prime95 ignores it as well. George has written sometime ago that such behaviour will be corrected in the next version. But that shouldn´t be keeping you from running more than one P-1 test on a multi-core machine. The worker windows will share the available memory evenly, according to each other needs. I have been running, for several months now, P-1/P-1 on a dual core CPU with no problems at all. I´ve allocated 1200 Mb of mem to Prime95, and when one window is running Stage 1 and the other Stage 2, the latter takes around 1140 Mb. When both are running Stage 2, each one takes ~600 Mb. The program manages the mem allocation automatically
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Old 2010-03-10, 02:03   #18
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Quote:
Originally Posted by lycorn View Post
The current version (25.11) of Prime95 ignores it as well.
Website say it is version 25.9
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Old 2010-03-10, 14:01   #19
lycorn
 
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25.11 is available here:
http://www.mersenneforum.org/showthread.php?t=12155
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Old 2010-03-27, 17:04   #20
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I am new to PrimeNet and have recently enlisted a dedicated quad core machine with 4 GB of RAM to find a prime. Here're some basic questions:

1. When the cores first started working, it was looking for small factors. What is the acronym for this work?

2. I've seen the memory allocating activity on the screen so I assume this is P-1 work. Is this where the mersenne's equation is being calculated?

3. The results record show that P-1 is completed and now it is doing LL work.

4. What does DC, D, and ECM mean? I believe TF means trial factoring.

5. When a computer receives an exponent, does PrimeNet allow the same computer to continue working on the same number until it is determined to be a prime or not?

6. From the discussion above, it appears that a person who is strictly after the reward for finding a large prime number could just ask for LL assignments. Is this correct?

Last fiddled with by esqrkim on 2010-03-27 at 17:07
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Old 2010-03-27, 18:50   #21
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Quote:
Originally Posted by esqrkim View Post
I am new to PrimeNet and have recently enlisted a dedicated quad core machine with 4 GB of RAM to find a prime. Here're some basic questions:

1. When the cores first started working, it was looking for small factors. What is the acronym for this work?
either TF or P-1
Quote:
2. I've seen the memory allocating activity on the screen so I assume this is P-1 work. Is this where the mersenne's equation is being calculated?
P-1 is another way to find relativly small factors.
Quote:
3. The results record show that P-1 is completed and now it is doing LL work.
this is not a question.
Quote:
4. What does DC, D, and ECM mean? I believe TF means trial factoring.
DC is Double Check. It basicly repeats the LL test to make sure no errors occured.
ECM stand for Eliptic Curve Method and is another way to find small factors.
Quote:
5. When a computer receives an exponent, does PrimeNet allow the same computer to continue working on the same number until it is determined to be a prime or not?
ya, so long as it keeps working on it a reporting in periodically it keeps that exponent exclusivly.
Quote:
6. From the discussion above, it appears that a person who is strictly after the reward for finding a large prime number could just ask for LL assignments. Is this correct?
Well, they could but that would be anti-social. The LL-only category is intended for people running other programs(other that prime95 or mprime, there are several) who do not have the TF or P-1 implemented to run exclusively LL tests. Also I guess if you have very little memory available you might prefer not to run P-1.
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Old 2010-03-27, 19:19   #22
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Edit: Oops, lfm posted several minutes before I finished composing this.

I have no quarrel with any of lfm's answers except the last one, in reply to esqrkim's #6. I don't see how esqrkim's #6 is anti-social. It's perfectly okay to want to test a number eligible for the next EFF prize. That's why the "LL-100M" type of request was made available in PrimeNet! Perhaps lfm may be confusing the "LL" assignment type with the "LL-NF" assignment type.

Or maybe I'm misinterpreting esqrkim's #6 and he _is_ asking about "LL-NF", and lfm's response _is_ appropriate. Only esqrkim can tell.

- - -

Quote:
Originally Posted by esqrkim View Post
1. When the cores first started working, it was looking for small factors. What is the acronym for this work?
The first factoring method used is trial factoring, TF. A second method, P-1 factoring (PM1), could also find "small" factors, depending on the definition of "small".

Quote:
2. I've seen the memory allocating activity on the screen so I assume this is P-1 work. Is this where the mersenne's equation is being calculated?
No, but what you mean by "mersenne's equation" is unclear. There's not some standard "mersenne's equation".

P-1 is a factoring method invented by John Pollard. See http://en.wikipedia.org/wiki/Pollard...92_1_algorithm It uses a mathematical method called Fast Fourier Transform (FFT) to perform multiplications.

Quote:
4. What does DC, D, and ECM mean?
DC (and D) = Double-checking. ECM = Elliptic Curve Method, another factoring method.

Quote:
I believe TF means trial factoring.
Correct.

Quote:
5. When a computer receives an exponent, does PrimeNet allow the same computer to continue working on the same number until it is determined to be a prime or not?
First of all, PrimeNet can't control what a user's computer does. You can use any computer at any time to test a number for primality -- if you don't care about overlapping/duplicating someone else's work, which can cause hard feelings and constitutes "poaching" if done deliberately.

What PrimeNet can do is assign work so that no one is "officially" working on the same number as anyone else who's working on a PrimeNet assignment. It's basically a voluntary cooperative system.

The contract between PrimeNet and you is:

1. In return for your requesting assignments and working only on assigned exponents, PrimeNet will do what it can to assure that it assigns no one else the same number at the same time.

2. You agree to report your result to PrimeNet in a timely manner so it can later on assign that number to someone else for further work, if needed.

3. If you don't report either a result, or progress toward a result, within the posted time limit (currently every 60 days), PrimeNet reserves the right to reassign the exponent, on the assumption that you've abandoned work on the assignment.

Now, there are different types of PrimeNet assignment. If PrimeNet assigns work as TF, it expects you to quit working on that number after you report your TF result (because PrimeNet will assume that after your TF report, it is free to assign that number to someone else for different work). Same for PM1 and ECM .

LL and DC(D) are a bit different -- if your prime95 program decides that not enough TF and PM1 work has been done yet on the exponent, it can proceed to finish up TF and/or PM1 before starting the long L-L (Lucas-Lehmer) test. This is okay with PrimeNet.

Quote:
6. From the discussion above, it appears that a person who is strictly after the reward for finding a large prime number could just ask for LL assignments. Is this correct?
Almost.

Because the next unclaimed EFF prize is for numbers larger than 100 million digits, he needs to specify "LL-100M".

If he specifies "LL" or "LL-WR" or "LL-NF", he'll be assigned an exponent for a number smaller than 100 million digits. ("LL-10M" is now obsolete, meaning only the same as "LL", because all current first-time assignments are exponents for more-than-10-million digit numbers.)

Since the current world record Mersenne prime has (many) less than 100 million digits, specifying "LL-WR" does _not_ guarantee being assigned an exponent eligible for the next EFF prize.

Last fiddled with by cheesehead on 2010-03-27 at 19:56
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