20040316, 22:37  #1 
May 2003
262_{10} Posts 
Speed Issue
I have been doing AdvancedFactor on a range for LMH (240250M), and others on this forum hinted that I may be experiencing speed problems. I am using Prime95 on a 900MHz Athlon with ~750MB RAM. I am using WellBehavedWork=1 and not using the computer for anything else. Also, the worktodo.ini line is
AdvancedFactor=240000000,250000000,0,32. My computer has progressed from 240000000 to 240075000 in 24 days. Is there anything I can do to improve the speed? On the plus side, I am noticing a 5060% elimination rate for prime exponents. Spotchecking has shown them to be legitimate candidates. ThomRuley 
20040316, 23:47  #2 
Feb 2003
10100011_{2} Posts 
Sounds very strange. On my Athlon 1.2G it took 768 s to do AdvancedFactor=250000000,250010000,0,55 (571 prime exponents tested, 319 eliminated, ie. 55.%). Extrapolated to a range of 75000 for your system it should take about 22.5 h. If you factor only to 32 bit it takes just few minutes but the expected rate of exponents eliminated in your range I guess is then around 10 %. So I think something is wrong. Have you factored maybe to 62 bit ? My timings have been obtained under Win with version 21.4 (same timings as 21.3). Another reason might be another process consuming all the CPU time (Prime95 runs with lowest priority), but OTOH this is contradictory to the percentage of exponents eliminated.
Last fiddled with by hbock on 20040317 at 00:02 
20040317, 04:12  #3 
May 2003
2·131 Posts 
Something else I failed to mention. My entire worktodo.ini file:
AdvancedFactor=240000000,250000000,0,32 AdvancedFactor=240000000,250000000,33,50 AdvancedFactor=240000000,250000000,51,60 AdvancedFactor=240000000,250000000,61,70 Could the other lines be causing a problem? I had noticed that some of the factors found were larger, much larger than 2^32. ThomRuley 
20040317, 22:08  #4 
Feb 2003
163 Posts 
Ok, this explains a lot. Your factoring levels are very high. 5060 bit maybe finished or not but factoring to 70 bit is too high I guess. If you really want to continue (AFAIK nobody else did that in these ranges) test smaller steps like 6162 etc. or change to another range.
Maybe there is also a problem with your result file, size could be 100M meanwhile or higher. The first two steps (032 and 3350bit) should be finished anyway and result in a file of at least 60 MB, so it's better to separate the results in several files. Regarding speed, remember every bit factoring depth more costs at least twice the time so you can estimate a practical limit. 
20040318, 04:15  #5 
May 2003
2·131 Posts 
I cut out those other lines already. I haven't had a chance to check whether that helped.
I haven't noticed that it slowed down as the results file expanded, but I'll try moving those lines to another file. Any other suggestions will be greatly appreciated. Thanks ThomRuley 
20040319, 00:50  #6 
May 2003
406_{8} Posts 
I tried cutting out the additional lines in worktodo.ini and moving results to another file, but these didn't seem to help.
I just tried reinstalling Prime95 to see if that helps. On a possibly related note, I have been having trouble with Windows on that machine. Could that be causing some of the problem? ThomRuley 
20040319, 01:02  #7  
Nov 2003
3·5·11 Posts 
Quote:


20040319, 15:12  #8 
May 2003
106_{16} Posts 
Thanks, I'll try that. I also found another solution. I replaced all my lines in worktodo.ini with AdvancedFactor=240000000,250000000,0,60. I also handed some of the range to my newer, faster computer. That should speed things up a bit.

20040321, 23:46  #9 
Feb 2003
163 Posts 
Sorry, I can't understand what happend. Can you tell us the size of your first results file after 24 days of running. What are the last lines of this file (hope you saved it), ie. how much was the progress (Mxxxxxxx has no factor from ....to 2^yy). You told us that some factors found have been much larger than 2^32, so factoring to 50 bit or maybe 60 bit is already finished !
If you start now again from 060 bit much less factors will be found because if a small factor is found on a distinct level no further search, ie. to 60 bit, will be carried out and next exponent is tested. OTOH by this means Advancedfactor 060 might be faster as factoring from 5060 bit with much less factors found but the number of exponents eliminated remains the same. 
20040322, 00:00  #10 
May 2003
106_{16} Posts 
Strangely enough, I didn't notice a change in speed when I condensed all my worktodo.ini lines to 060.

20050426, 22:18  #11 
Jul 2004
Nowhere
809 Posts 
60 is rather high it will take about 1 minute per factor at 60 alone susgest going to 50

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