Factoring so slow??

xtreme2k · 2003-03-11, 18:10

I am going to run a LLtest of M33395827. However after 2 days of factoring (around 50 hours up to now, 80-85% cpu time - I am guessing here) prime still havent start to actual LL test. It has completed the initial trial factoring to 2^68 and currently its doing some 'Stage 1' thing and at around 65%.

The computer is a P4 2.4@3.1 with 2GB RAM, 1GB given to prime.
Is there something wrong or am I just being too impatient?

garo · 2003-03-11, 18:39

Nothing's wrong. It takes about 2 days to do trial factoring to 68 bits and currently your machine is doing a P-1 test which goes in two stages. The LL test should start in another day or so - if P-1 does not find a factor.

lycorn · 2003-03-11, 18:47

And also, as you have given 1GB to prime95, it can be anticipated a long time waiting for Stage 2 of P-1 to finish. The good point is that the chances of finding a factor are higher.

trif · 2003-03-11, 19:34

And if you find a factor, you have just eliminated a very expensive LL test (and the doublecheck!). This means you can move on more quickly to an exponent that just might yield that whopper of a prize.

xtreme2k · 2003-03-11, 19:47

Thanks for the response :)

Previously I have only been running Double checking on this system as it only takes a few days per test on those. Now I might want to give LL test ago see how things are :)

lycorn · 2003-03-11, 23:06

Quote:

Previously I have only been running Double checking on this system as it only takes a few days per test on those.

Just out of curiosity, how do your system take to complete a DC in the current range (9M)? I use a P4 1,6 for DCs and it takes me just over 4 days. I reckon in your system it should take half of it.

xtreme2k · 2003-03-12, 04:44

Quote:

Originally Posted by lycorn

Quote:

Previously I have only been running Double checking on this system as it only takes a few days per test on those.

Just out of curiosity, how do your system take to complete a DC in the current range (9M)? I use a P4 1,6 for DCs and it takes me just over 4 days. I reckon in your system it should take half of it.

Yah it used to take about two and a half days for each LL test on the 9M range. Each iteration time is around 0.016sec.

QuintLeo · 2003-03-13, 04:12

Which is a lot of the difference - the 33M+ range takes a lot longer, and the iteration time is also a lot slower.

Even on a P4.

9-)

2003-03-11, 18:10	#1
xtreme2k Aug 2002 174₁₀ Posts	Factoring so slow?? I am going to run a LLtest of M33395827. However after 2 days of factoring (around 50 hours up to now, 80-85% cpu time - I am guessing here) prime still havent start to actual LL test. It has completed the initial trial factoring to 2^68 and currently its doing some 'Stage 1' thing and at around 65%. The computer is a P4 2.4@3.1 with 2GB RAM, 1GB given to prime. Is there something wrong or am I just being too impatient?

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2003-03-11, 18:39	#2
garo Aug 2002 Termonfeckin, IE 2²×691 Posts	Nothing's wrong. It takes about 2 days to do trial factoring to 68 bits and currently your machine is doing a P-1 test which goes in two stages. The LL test should start in another day or so - if P-1 does not find a factor.

2003-03-11, 18:47	#3
lycorn "GIMFS" Sep 2002 Oeiras, Portugal 3×491 Posts	And also, as you have given 1GB to prime95, it can be anticipated a long time waiting for Stage 2 of P-1 to finish. The good point is that the chances of finding a factor are higher.

2003-03-11, 19:34	#4
trif Aug 2002 2×101 Posts	And if you find a factor, you have just eliminated a very expensive LL test (and the doublecheck!). This means you can move on more quickly to an exponent that just might yield that whopper of a prize.

2003-03-11, 19:47	#5
xtreme2k Aug 2002 2·3·29 Posts	Thanks for the response :) Previously I have only been running Double checking on this system as it only takes a few days per test on those. Now I might want to give LL test ago see how things are :)

2003-03-13, 04:12	#8
QuintLeo Oct 2002 Lost in the hills of Iowa 2⁶×7 Posts	Which is a lot of the difference - the 33M+ range takes a lot longer, and the iteration time is also a lot slower. Even on a P4. 9-)