20181108, 12:47  #1 
Random Account
Aug 2009
Not U. + S.A.
2,383 Posts 
ECM Stage 2 RAM
As most know, the minimum RAM size for any stage 2 process in Prime95 is 8MB. Assignments are based on whatever the amount is As I take the size up, the exponent values increase. When this happens, the smaller exponents, < 100,000, are eventually bypassed. Is there a way to compensate for this?

20181108, 16:01  #2 
1976 Toyota Corona years forever!
"Wayne"
Nov 2006
Saskatchewan, Canada
1010001110011_{2} Posts 
This might be a new "feature".
Several years ago I used to set RAM really now; get assigned a bunch of LOW ECM work; stop Prime95 and increase the RAM and start it so they would finish faster. 
20181108, 16:30  #3  
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Aug 2009
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2,383 Posts 
Quote:
The cutoff seems to be in the 48MB to 64MB range. This is not a problem with smaller exponents, regardless of the RAM setting. By smaller, I mean anything at, or below, six digits. What it does during these pauses, I have not a clue. All I can say is that there is no hard drive activity and everything else responds properly. This applies to Windows 7 and 10, both x64. Perhaps I need to do some experimentation with the RAM settings in the BIOS. Something is amiss and I would like to find it. 

20181108, 22:42  #4 
"Victor de Hollander"
Aug 2011
the Netherlands
3^{2}·131 Posts 
Maybe I don't understand your question entirely, but if you want to manually do ECM on a exponent, you can just add it to your queue with:
ECM2=1,2,exponent,1,B1,B2,numbersofcurves,"knowfactorn,knownfactor" for instance: ECM2=1,2,1682911,1,250000,25000000,3 will let Prime95 do 3 ECM curves on 2^16829111 with B1=250e3 B2=25e6 
20181109, 00:05  #5 
"GIMFS"
Sep 2002
Oeiras, Portugal
2×3^{3}×29 Posts 
Seconded.
If you do that, you may test whatever exponent you wish, regardless of the RAM size assigned to Prime95. Of course, if you are testing very small exponents, the amount of RAM needed will be very low, but it´s good practice to have a generous amount assigned to Prime95, in case you decide to test larger exponents. I am curently running curves on M8581, and the program is using only 431 MB for Stage 2, but this is a very small exponent. If you test exponents in the 2M range, for example, the amount of RAM used wll jump to a couple of gigabytes. Last fiddled with by lycorn on 20181109 at 00:06 
20181109, 00:37  #6 
1976 Toyota Corona years forever!
"Wayne"
Nov 2006
Saskatchewan, Canada
12163_{8} Posts 
I did this a while back because I didn't want the hassle of manually entering assignments.
In my case I wanted ECMFermat assignments and I noticed that for my specific PC that GhzDays per Day was noticeably more generous with the smaller assignments (up to about 131072) but I also noted that the RAM I needed to specify for Prime95 to give me assignments this low was less than ideal to quickly complete these. So I would set RAM to about 100; get 30 days worth of low ECMF; then set RAM to about 2,000. Rinse and repeat monthly. 
20181109, 13:12  #7  
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Aug 2009
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2,383 Posts 
Forgive me. I went a bit off target with this.
Quote:
I found something in relation to the pausing in stage 2. This system BIOS has two memory settings, Auto, and XMP or "eXtreme Memory Profile." Setting it to XMP creates a dropdown list of options which includes the RAM speed. The rest, I do not understand what they are. No worry. On the XMP setting and not changing anything else in the list, the pause times are greatly reduced. I have been testing with the RAM set to 512MB and exponents > 1,000,000. The pause time is about 1.1 seconds for every 7%. It can complete each test in about eight minutes. If I drop this to 256MB, it takes nine minutes to complete on slightly smaller exponents. I do not see any pauses. About setting it to get 30 days of work: In my case, 15 is about the maximum number that it will maintain. I will give this another try. 

20181110, 15:08  #8 
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Aug 2009
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4517_{8} Posts 
A couple of questions:
Take the assignment below from my HP: Code:
ECM2=<ID>,1,2,109229,1,250000,25000000,3,"7680983281,2929719921407" (2) Is there a ruleofthumb for determining the B! and B2 values? All I know is that B2 is approximately equal to B1 x 10. Thank you! 
20181110, 16:09  #9  
Sep 2003
13×199 Posts 
Quote:
Note: if the program finds a new factor not in the list of known factors, then the ECM assignment will terminate, unless you put ContinueECM=1 in your prime.txt file, in which case it will finish doing all the curves specified in the worktodo line (in your example, 3), possibly finding additional factors. Quote:
You can look at the ECM Progress report page, setting the appropriate exponent range you're interested in, to see how much ECM has been done already and with what parameters. Last fiddled with by GP2 on 20181110 at 16:15 

20181110, 17:02  #10  
Random Account
Aug 2009
Not U. + S.A.
2,383 Posts 
Quote:
My example shows 250,000 and 25,000,000. What happens if I were to narrow this range? An example might be lowering B2 to 2,500,500. Based on what I've seen, B1 seems to be much more important than B2. A shotinthedark: These are bounds for calculations using the seed value that appears at the start of Stage 1. If this is not the case, then I am unsure how they are used. I apologize for going somewhat offtopic with this! 

20181110, 17:30  #11  
"Forget I exist"
Jul 2009
Dartmouth NS
20342_{8} Posts 
Quote:


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