20130904, 08:40  #1 
Jul 2013
3·5 Posts 
Factoring 110 digits in 38 hours !
I have been running msieve151 (last version) and trying to factor a 110digits number, it managed to find the 2 factors but the problem is it took too much time (about 40 hours ) ,, which means i will wait forever to solve a 170digit number.My Questions are:
Is this normal ? my computer is i7 with 8 gigabytes Ram ,, running windows 7 64bit How can i optimize this tool to get it more efficient,, i quote this from another thread : ******************************************************************************************************************* firejuggler to give you an idea: A modern CPU and working on 3 coreone computer. a C110C115 is a matter of 2 or 3 hours, a C115C120 half a day; C120C125 a day, C125C130 two to three day, C130C135 a week... roughly doubling the time for 5 or 6 digits. prgamma10 With both cores of my Core i5 (64bit ASM siever), a GNFS 125 job takes a day, and a GNFS 135 job takes 3 days (poly selection time included). ******************************************************************************************************************* I dont know why did it take all this time although it solved the 100digit number in about 4 hours only!also 4 hours is much time but even doubling it twice doesn't reach this 40 hours range.. Last fiddled with by mohamed on 20130904 at 08:41 
20130904, 11:37  #2 
Jan 2013
109_{10} Posts 
You should not use the siever in Msieve anyway.
People use the factmsieve.py script (and a combination of GGNFS and Msieve) for small numbers (95140 digits). Last fiddled with by prgamma10 on 20130904 at 11:41 
20130904, 13:32  #4 
I moo ablest echo power!
May 2013
5·349 Posts 
Seconding Jeff Gilchrist's site as a fantastic starting point. Once you understand that stuff, you can start playing around with other options.

20130904, 16:29  #5 
Tribal Bullet
Oct 2004
2·29·61 Posts 
Actually if you just use Msieve with no options, you would be using the quadratic sieve to factor a 110digit input. The line sieve in Msieve doesn't even work anymore.
Last fiddled with by jasonp on 20130904 at 16:29 Reason: speeling 
20130905, 09:52  #6 
Jul 2013
15_{10} Posts 
Could you please tell me how to use options ?
or where to start reading about how to control this tool because i found many stuff but i got stuck and couldn't reach what is the starting point to fully understand this fantastic tool.. 
20130905, 10:57  #7  
Nov 2003
2^{2}·5·373 Posts 
Quote:
what the options and parameters mean without understanding the algorithm. Do you know how to use command line driven software? e.g. how to list the options by invoking the help option? 

20130905, 11:58  #8  
Account Deleted
"Tim Sorbera"
Aug 2006
San Antonio, TX USA
1000010101011_{2} Posts 
Quote:


20130907, 09:47  #10 
Jul 2013
F_{16} Posts 
Good news(for me actually) is that when I used cuda the time needed decreased to 2.5 hours only ! (what a significant performance increase),,
using GPU 0 (GeForce GTX 560) Here is some info Number: example Code:
N = 33319100065905904618088073943717337775739127140720065000985127089174658538966168614190493840451006968337649739 (110 digits) Divisors found: r1=2425967623052370772757633156976982469681 (pp40) r2=4384165182867240584805930970951575013697 (pp40) r3=53542885039615245271174355315623704334284773568199 (pp50) r4=622288097498926496141095869268883999563096063592498055290461 (pp60) Version: Msieve v. 1.51 (SVN unknown) Total time: 2.28 hours. Factorization parameters were as follows: n: 33319100065905904618088073943717337775739127140720065000985127089174658538966168614190493840451006968337649739 Y0: 836927139885417757727 Y1: 104390864471 c0: 2609428838573120977025316 c1: 6455109638585727585738 c2: 605367217999925363 c3: 73299778283069 c4: 2107091359 c5: 81144 skew: 15521.55 type: gnfs Factor base limits: 3200000/3200000 Large primes per side: 3 Large prime bits: 27/27 Sieved algebraic specialq in [0, 0) Total raw relations: 8256248 Relations: 537820 relations Pruned matrix : 330082 x 330307 Polynomial selection time: 0.10 hours. Total sieving time: 2.07 hours. Total relation processing time: 0.03 hours. Matrix solve time: 0.05 hours. time per square root: 0.02 hours. Prototype defpar.txt line would be: gnfs,109,5,61,2000,0.00015,0.3,250,15,50000,2400,3200000,3200000,27,27,50,50,2.6,2.6,100000 Intel64 Family 6 Model 45 Stepping 7, GenuineIntel Windows76.1.7600 processors: 8, speed: 3.60GHz actually I have 2 cuda cards,, is it available to use both of them during the same run ? how ? I am reading now more about msieve and the algorithms it uses ,, i am a fresh graduate from faculty of engineering so i have a lot to read (a lot really!) Thanks all for your help and if anyone told me how to enable using both card it would be great really.. Last fiddled with by wblipp on 20130910 at 17:21 Reason: Added code box 
20130908, 06:28  #11 
"Curtis"
Feb 2005
Riverside, CA
2×2,393 Posts 
CUDA only helps with polynomial selection. Yes, in principle you could use two CUDA cards with two separate copies of msieve running but look at the amount of time you spent on poly select in this example; it's not worth the effort to manually run poly select on two cards until perhaps C145 or bigger.

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