P-1 before LL - Page 3

LaurV · 2013-11-01, 17:30

Quote:

Originally Posted by Prime95

That advice may not hold for the GPU. The breakeven point depends on the relative speed of TF and P-1 on the GPU. Choose your next task (P-1 or TF) based on which will find factors more efficiently.

Say the P-1 job with 4% chance of success takes 8 hours -- that's one factor every 8.33 days. Say TF to the next bit level takes 2 hours -- that's one factor every 74/12 = 6.17 days. So TF to next bit level is best.

Plug in you GPU's actual P-1 and TF times to reach the correct conclusion for your own GPU.

BTW, this advice can be superceeded by other factors. If GIMPS as a whole has a shortage of P-1 GPUs and an excess of TF GPUs, then it is better to do the next TF level as it reduces the amount of P-1 work to be done.

Sure, that was exactly what I said: everybody has to do his homework.

Except that I put "realistic" numbers into the calculus (~160 minutes per P-1 assignment, about 80 minutes per each stage). If it would take 6 days to eliminate one exponent, by either TF or P-1, than you would be better doing LL directly. The 580 needs below 100 hours for a front range LL.

What we still can discuss is the balance between B1 and B2, especially if we would have the possibility to "extend" a B1. But that is another story.

For the last paragraf of your post, see where I said I do P-1 because I am afraid few bad guys will push me out of lifetime top 100

I just stepped up 6 places today, and I am going to stop when I will get into 100 percentile. Which will be in about 10 days. Can you see a better reason? :P

TheMawn · 2013-11-01, 20:42

Regarding documentation:

I too have many times had questions which could easily have been answered by a little document saying here's how many exponents are where and here's how many were brought to and from these stages in the last week, or whatever.

It would be a lot of work and I personally am not volunteeering for the job

Also the fact that P-1 isn't done at a specific stage makes things a bit tougher, because you have 74 bits P-1, 74 bits no P-1, 73 bits P-1, 73 bits no P-1, etc.

Best just keep regularly checking that things are progressing at relatively smooth rates. I.e., if P-1 is getting one day ahead of TF every twenty days, then it practically never becomes a real issue.

LaurV · 2013-11-02, 04:06

You mean something like this, or this? (see also James' site). Or something specifically related to P-1?

TheMawn · 2013-11-02, 04:51

I am aware of those tables. But, yeah. Something with some P-1 information would be cool but I am completely aware of the effort required to make something "just because it would be neat." I think there's just too much information and not enough dimensions to have it all graphed up in one place so it's a lot of jumping back and forth to try to make sense of the data.

Ah well. I think it's good enough for me if someone like Chris can just give us a heads-up when something starts to fall behind or whatever.

TheMawn · 2013-11-02, 05:01

Looking further into those graphs I can see the remains of some of my work. A week and a bit ago I went and grabbed 50,000 exponents starting at 400M to trial factor. I've done this sort of thing before. I donno. I just get the bug. I brought 50,000 exponents from 66 to 68 (the same ones I brought to 66 from 65 a while back) which took a bit longer and generated less lines of results. Also staying away from the 65 to 66 wavefront helped avoid poaching as I can tell the 200M range is getting a good bit of activity.

You can see a big weird slightly-below-50,000 number of exponents TF'ed to 68 in the 400M. That would be me. Even on the primenet summary there's a slight amount more factors-found at 400M and 401M.

It's interesting to think that all that work found 1000 factors out of 50,000 candidates. It took about a week, and that was the easiest 2% of the remaining candidates to clear. For a range of two million exponents.

Man, this project is massive.

lycorn · 2013-11-02, 16:32

I hear what you said about the "bug". I get a different one from time to time. It´s nearly 12 years since I joined the project, so I really need to change the type of work from time to time. I had my DC phase, P-1 phase, TF phase, etc, most of the time tempered with some 1st time LLs. Over the last few months, I got a new bug, one I had never had: to work in the "lower end of the spectrum", i.e. TFing exponents that are below 65, and doing ECM on small exponents. Yeah, I know it´s most of it quite useless, and some years ago I was strongly against this "beating the dead horse" exercise, but hey, that´s life. For a couple of months more I think I will stick to it, using some old hardware parts. It´s one of the good things about these massive projects: plenty to choose from...

cheesehead · 2013-11-07, 22:59

Quote:

Originally Posted by Mark Rose

It would be excellent if that information were posted in a single place on some page: a simple table to say if you have X kind of hardware to use, put it to Y use.

Quote:

Originally Posted by TheMawn

Regarding documentation:

I too have many times had questions which could easily have been answered by a little document saying here's how many exponents are where and here's how many were brought to and from these stages in the last week, or whatever.

It would be a lot of work <snip>

I recommend that anyone volunteering to make such documentation, place it on mersennewiki.org

2013-11-01, 20:42	#24
TheMawn May 2013 East. Always East. 11×157 Posts	Regarding documentation: I too have many times had questions which could easily have been answered by a little document saying here's how many exponents are where and here's how many were brought to and from these stages in the last week, or whatever. It would be a lot of work and I personally am not volunteeering for the job Also the fact that P-1 isn't done at a specific stage makes things a bit tougher, because you have 74 bits P-1, 74 bits no P-1, 73 bits P-1, 73 bits no P-1, etc. Best just keep regularly checking that things are progressing at relatively smooth rates. I.e., if P-1 is getting one day ahead of TF every twenty days, then it practically never becomes a real issue.

2013-11-02, 04:06	#25
LaurV Romulan Interpreter Jun 2011 Thailand 2⁶·151 Posts	You mean something like this, or this? (see also James' site). Or something specifically related to P-1?

2013-11-02, 04:51	#26
TheMawn May 2013 East. Always East. 11×157 Posts	I am aware of those tables. But, yeah. Something with some P-1 information would be cool but I am completely aware of the effort required to make something "just because it would be neat." I think there's just too much information and not enough dimensions to have it all graphed up in one place so it's a lot of jumping back and forth to try to make sense of the data. Ah well. I think it's good enough for me if someone like Chris can just give us a heads-up when something starts to fall behind or whatever.

2013-11-02, 05:01	#27
TheMawn May 2013 East. Always East. 11010111111₂ Posts	Looking further into those graphs I can see the remains of some of my work. A week and a bit ago I went and grabbed 50,000 exponents starting at 400M to trial factor. I've done this sort of thing before. I donno. I just get the bug. I brought 50,000 exponents from 66 to 68 (the same ones I brought to 66 from 65 a while back) which took a bit longer and generated less lines of results. Also staying away from the 65 to 66 wavefront helped avoid poaching as I can tell the 200M range is getting a good bit of activity. You can see a big weird slightly-below-50,000 number of exponents TF'ed to 68 in the 400M. That would be me. Even on the primenet summary there's a slight amount more factors-found at 400M and 401M. It's interesting to think that all that work found 1000 factors out of 50,000 candidates. It took about a week, and that was the easiest 2% of the remaining candidates to clear. For a range of two million exponents. Man, this project is massive.

2013-11-02, 16:32	#28
lycorn "GIMFS" Sep 2002 Oeiras, Portugal 2·11·67 Posts	I hear what you said about the "bug". I get a different one from time to time. It´s nearly 12 years since I joined the project, so I really need to change the type of work from time to time. I had my DC phase, P-1 phase, TF phase, etc, most of the time tempered with some 1st time LLs. Over the last few months, I got a new bug, one I had never had: to work in the "lower end of the spectrum", i.e. TFing exponents that are below 65, and doing ECM on small exponents. Yeah, I know it´s most of it quite useless, and some years ago I was strongly against this "beating the dead horse" exercise, but hey, that´s life. For a couple of months more I think I will stick to it, using some old hardware parts. It´s one of the good things about these massive projects: plenty to choose from...