20150612, 17:41  #111 
"Phil"
Sep 2002
Tracktown, U.S.A.
3×373 Posts 
This is what I thought, too, but Ernst and I did some calculations a few years back that indicated it was generally worthwhile to spend on the order of 56% or so of your total ECM effort on Mersenne or Fermat numbers to run P1 to high limits. I was surprised that the percentage was that high, but the fact that some factors of P1 were already known boosted the success probability considerably. I would guess that for generic numbers this percentage would be lower.

20150613, 03:18  #112  
Serpentine Vermin Jar
Jul 2014
D05_{16} Posts 
Quote:
I only asked because I was lurking on the forum where they were talking about the 332M333M range (or whatever...I'm sure that's not exactly right). The concept of factoring some grandfathered LL assignments in that range came up, and I'd noted that quite a few of those assignments hadn't had any P1 done at all. They were going to do some extra TF work on them up to 79 bits or something and I just wondered about the feasibility of doing the P1 work on some of my systems with lots of RAM. I have zero builtin idea of how long it takes to run P1 work at all in that range, for any B1/B2 values, so I thought I'd first see if GMPECM would be advantageous. 

20220703, 16:12  #113 
Aug 2020
79*6581e4;3*2539e3
2^{3}·73 Posts 
I am currently running stage 1 ECM on M22543 with B1=3M with 9 workers.
I noticed they all write their residues to results.txt. I then checked GMP ECM's loop option and found that it specifically is incompatible with resume. So how do I run several instances of GMPECM parallel for stage 2? Or isn't this possible? If not, can I salvage the stage 1 residues for an mprime stage 2 run? Doing 4000 curves on one core would take a bit too long... :) Last fiddled with by bur on 20220703 at 16:13 
20220703, 19:52  #114 
"Oliver"
Sep 2017
Porta Westfalica, DE
2^{6}×17 Posts 
You would need to divide the stage 1 residues into n seperate files, then start n processes of GMPECM, each with their own file. Please be beware that this might use more memory than you have! In this case, you would need to use the maxmem switch.

20220704, 06:09  #115 
Aug 2020
79*6581e4;3*2539e3
2^{3}·73 Posts 
Your reply sounds like this is not usually done, I can imagine due to the additional manual work. I'm wondering if splitting work over prime95/gmpecm is worth it for small numbers of curves and small B1.
Is there a table or similar for timings difference of prime95 vs gmpecm? 
20220704, 12:16  #116 
"Oliver"
Sep 2017
Porta Westfalica, DE
2^{6}×17 Posts 
In this case, I can only comment on how frequent I am doing it like this, but when I have a lot of curves that should go to GMPECM, I will definitely do it the way I described for the reasons you mentioned. If it is more than one or two days of work on a single core, I would deem it beneficial. For less than that, I would not care to spend manual work on it. But this is my personal preference.
Since we now got 30.9 as a (pre?) beta or alpha, such a table would change drastically. For 30.8 and older, I had better stage 2 even with exponents as large as 200k. In this case, one should experiment, but as George said, up to 50k, GMPECM is definitely the better choice. 
20220704, 16:43  #117 
Aug 2020
79*6581e4;3*2539e3
2^{3}×73 Posts 
Ok, thanks, that leaves the question of how to report the results. In the early posts of this thread the solution was "mail it to George" who already then was understandably reluctant.
Can I just tailor a report.json.txt entry? Last fiddled with by bur on 20220704 at 16:53 
20220704, 16:52  #118  
"Oliver"
Sep 2017
Porta Westfalica, DE
2^{6}·17 Posts 
Quote:
Edit: Your JSON would have a wrong/missing checksum. Last fiddled with by kruoli on 20220704 at 16:53 Reason: Additions. 

20220704, 18:19  #119 
"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest
1A11_{16} Posts 
For reporting gmpecm ECM results manually, see http://www.mersenneforum.org/showthread.php?t=23143 posts 2, 5, 8
post 2 (Prime95): "You have to reformat the results to look like it came from prime95. The manual results web page will then complain that the checksum isn't right. However, I can add you to the trusted users list and have that web page accept your results anyway." 
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