20181106, 00:38  #1 
1976 Toyota Corona years forever!
"Wayne"
Nov 2006
Saskatchewan, Canada
13·349 Posts 
Number of relative primes for P1
Now that I am doing a lot of P1 I'm intrigued by the number of relative primes
Code:
[Nov 5 17:57] Available memory is 3151MB. [Nov 5 17:57] Using 3141MB of memory. Processing 144 relative primes (259 of 960 already processed). At one time I thought it might be some magical function of the exponent range...until yesterday. I have a PC working on P1 in the 47.2M range and for 5 days it was doing 480 relative primes; which by the way is the most common value I've seem for P1. However, last night I changed the CPU setting to increase RAM overnight (it is now 16G daytime and 20G overnight). Since then the P1 work on this same PC is now doing 960 rp's. Now I am thinking the value is a function of the RAM allocated. I am going to further assume it is a function of the maximum RAM; otherwise assignments starting during the day (when I have 16G) would get 480 rp's and 960 rp's when started overnight. Am I anywhere close is my guesses? Is there a layman's answer to this question? Last fiddled with by petrw1 on 20181106 at 00:39 
20181106, 02:01  #2  
Jun 2003
2×2,423 Posts 
Quote:
However, there is not significant difference in performance between 16G and 20G of allocation. In fact, if an assignment crosses the day/night boundary (in either direction), it will stop and restart with new memory settings, and will cause so much additional work that it will wipe out any potential gains. Please stick with one setting for the entire day. 

20181106, 02:15  #3 
"Mike"
Aug 2002
5·7·227 Posts 
In the 87M range, 12GB is enough to get the "E=12" BrentSujama thingie.
Related thread: https://www.mersenneforum.org/showthread.php?t=23331 
20181106, 02:49  #4  
1976 Toyota Corona years forever!
"Wayne"
Nov 2006
Saskatchewan, Canada
11B9_{16} Posts 
Quote:


20181107, 20:20  #5 
1976 Toyota Corona years forever!
"Wayne"
Nov 2006
Saskatchewan, Canada
1000110111001_{2} Posts 
P1 with 20GB is slower than 16GB
After a couple days at 20GB of RAM instead of 16GB I am seeing:
 960 relative primes INSTEAD of 480 relative primes  same GhzDays credit  BUT it is not taking a little longer. With a total of 480 RPs stage 2 was taking almost exactly 1 minute per RP. i.e. if it was doing 60 RPs it took 60 minutes. But with a total of 960 RPs it is taking MORE THAN 2 minutes per RP. i.e. if it is doing 60 RPs it is taking about 135 minutes and so the entire P1 is taking longer overall. Seems odd that I am slowing down with MORE RAM. NOTE a typical assignment is: Code:
Pminus1=N/A,1,2,47299781,1,1000000,20000000,73 Hold the presses... After a more formal and official calculation it seems it made not enough difference to measure yet... Last fiddled with by petrw1 on 20181107 at 21:25 Reason: Hold the presses 
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