20100303, 18:14  #12  
Oct 2008
n00bville
5^{2}×29 Posts 
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20100303, 18:22  #13 
Account Deleted
"Tim Sorbera"
Aug 2006
San Antonio, TX USA
17·251 Posts 
Yes, but how often will machines that are mainly used for LL allow enough memory to have a really worthwhile P1 test? I don't really know, but I'm sure more factors are found when you get computers more dedicated towards P1 to do that part.

20100304, 08:59  #14 
Sep 2002
Oeiras, Portugal
2662_{8} Posts 
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 P1 work. Therefore, the probability of finding a factor is higher if you have "specialized" P1 factor hunters.
Note as well that P1 is performed on a given exponent before the final level of TF. If P1 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 P1 test at all; these correspond to people allocating small amounts of memory to P1 or even skipping the test altogether. Some of these tests (and the DC that will have to follow) could have been avoided had P1 been properly done. To summarize: the advantages of having P1 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. 
20100305, 04:10  #15 
Oct 2008
California
2^{2}×59 Posts 
mine are DC/P1/LL/LL

20100308, 22:41  #16 
Mar 2003
Melbourne
5×103 Posts 
2 machines  dc/dc/dc/p1 and dc/p1
I'd do more p1 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 
20100309, 18:50  #17 
Sep 2002
Oeiras, Portugal
2·3^{6} Posts 
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 P1 test on a multicore machine. The worker windows will share the available memory evenly, according to each other needs. I have been running, for several months now, P1/P1 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

20100310, 02:03  #18 
6809 > 6502
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Aug 2003
101×103 Posts
9,547 Posts 

20100310, 14:01  #19 
Sep 2002
Oeiras, Portugal
2·3^{6} Posts 
25.11 is available here:
http://www.mersenneforum.org/showthread.php?t=12155 
20100327, 17:04  #20 
Mar 2010
California, USA
2·13 Posts 
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 P1 work. Is this where the mersenne's equation is being calculated? 3. The results record show that P1 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 20100327 at 17:07 
20100327, 18:50  #21  
Jul 2006
Calgary
5^{2}·17 Posts 
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ECM stand for Eliptic Curve Method and is another way to find small factors. Quote:
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20100327, 19:19  #22  
"Richard B. Woods"
Aug 2002
Wisconsin USA
2^{2}·3·641 Posts 
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 antisocial. It's perfectly okay to want to test a number eligible for the next EFF prize. That's why the "LL100M" type of request was made available in PrimeNet! Perhaps lfm may be confusing the "LL" assignment type with the "LLNF" assignment type. Or maybe I'm misinterpreting esqrkim's #6 and he _is_ asking about "LLNF", and lfm's response _is_ appropriate. Only esqrkim can tell.    Quote:
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P1 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:
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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 LL (LucasLehmer) test. This is okay with PrimeNet. Quote:
Because the next unclaimed EFF prize is for numbers larger than 100 million digits, he needs to specify "LL100M". If he specifies "LL" or "LLWR" or "LLNF", he'll be assigned an exponent for a number smaller than 100 million digits. ("LL10M" is now obsolete, meaning only the same as "LL", because all current firsttime assignments are exponents for morethan10million digit numbers.) Since the current world record Mersenne prime has (many) less than 100 million digits, specifying "LLWR" does _not_ guarantee being assigned an exponent eligible for the next EFF prize. Last fiddled with by cheesehead on 20100327 at 19:56 

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