mersenneforum.org  

Go Back   mersenneforum.org > Factoring Projects > Operation Billion Digits

Reply
 
Thread Tools
Old 2010-08-02, 03:29   #1
lavalamp
 
lavalamp's Avatar
 
Oct 2007
Manchester, UK

53A16 Posts
Default Trial Factor Bit Depth

I am sure this must have been discussed before with regards to OBD, but I could not find it.

I have just made a post in which I extended the table of trial factor depths found on The Math page of mersenne.org all the way up to billion digit numbers.

Here's the post:
http://www.mersenneforum.org/showpos...1&postcount=70

I have included the methodology used to attain the numbers and I would appreciate any comments on it's validity.

If the numbers do turn out to be correct, then it looks like the OBD candidates need to be trial factored all the way to 87 bits, and currently there are 10 (soon to be 13) exponents at 81 bits.

In terms of levels, that's high enough to take the project to level 21.01, which at the minimum would require 22 candidates at 87 bits.
lavalamp is offline   Reply With Quote
Old 2010-08-02, 09:57   #2
ET_
Banned
 
ET_'s Avatar
 
"Luigi"
Aug 2002
Team Italia

12B616 Posts
Default

87 bits on one OBD exponent would require at least 4 months of 24/7 activity on a GXT275. I guess it's premature to reach that bit-depth with actual methods...

By the time GIMPS extends 6 times its bounds, I think we'd better check fornew factors than for bit-depth.

Luigi

Last fiddled with by ET_ on 2010-08-02 at 10:00
ET_ is offline   Reply With Quote
Old 2010-08-02, 13:17   #3
CRGreathouse
 
CRGreathouse's Avatar
 
Aug 2006

10111010010012 Posts
Default

Quote:
Originally Posted by ET_ View Post
By the time GIMPS extends 6 times its bounds, I think we'd better check fornew factors than for bit-depth.
That's how I feel. Anyone crunched this comparison?
CRGreathouse is offline   Reply With Quote
Old 2010-08-02, 15:05   #4
lavalamp
 
lavalamp's Avatar
 
Oct 2007
Manchester, UK

2·3·223 Posts
Default

Quote:
Originally Posted by ET_ View Post
87 bits on one OBD exponent would require at least 4 months of 24/7 activity on a GXT275.
I dunno, it might be nice to have 1 candidate taken all the way, call it a figurehead. 4 months is quite a while, but it's better than the 8 years and 5 months my overclocked i7 would take. A GTX 480 would take less time of course, but still a couple of months most likely.

Even so, it's good to know what the ultimate goal is. 87 seems tantalizingly close as the project has several candidates at 81 bits now. We all know of course that 87 bits requires another 63 times the work to reach, but that's not as much of a carrot as saying, "JUST 6 MORE!"

Quote:
Originally Posted by CRGreathouse View Post
Anyone crunched this comparison?
What do you mean by this?
lavalamp is offline   Reply With Quote
Old 2010-08-02, 15:26   #5
ET_
Banned
 
ET_'s Avatar
 
"Luigi"
Aug 2002
Team Italia

2·5·479 Posts
Default

Quote:
Originally Posted by lavalamp View Post
I dunno, it might be nice to have 1 candidate taken all the way, call it a figurehead. 4 months is quite a while, but it's better than the 8 years and 5 months my overclocked i7 would take. A GTX 480 would take less time of course, but still a couple of months most likely.
Maybe I'll give it a try as soon as winter approaches, we actually have 96/98 degrees in Rome. definitely too hot to run a GPU search 24/7.
But I don't recommend following my example!

The problem here is that, even using MORE_CLASSES, each class from 86 to 87 bits would last more than 3,5 hours, and interrupting the search to use the (otherwise unusable) computer would waste approximately 2 hours of calculations.


Quote:
Originally Posted by lavalamp View Post
Even so, it's good to know what the ultimate goal is. 87 seems tantalizingly close as the project has several candidates at 81 bits now. We all know of course that 87 bits requires another 63 times the work to reach, but that's not as much of a carrot as saying, "JUST 6 MORE!"


In 4 months' work we could bring 63 exponents to 80/81 bits...

Luigi
ET_ is offline   Reply With Quote
Old 2010-08-02, 15:52   #6
mdettweiler
A Sunny Moo
 
mdettweiler's Avatar
 
Aug 2007
USA (GMT-5)

3·2,083 Posts
Default

Quote:
Originally Posted by ET_ View Post
Maybe I'll give it a try as soon as winter approaches, we actually have 96/98 degrees in Rome. definitely too hot to run a GPU search 24/7.
But I don't recommend following my example!

The problem here is that, even using MORE_CLASSES, each class from 86 to 87 bits would last more than 3,5 hours, and interrupting the search to use the (otherwise unusable) computer would waste approximately 2 hours of calculations.
If the computer has integrated graphics available, you could always try running the monitor off that instead of the GPU. AFAIK, that will still leave the computer usable while the GPU is crunching.
mdettweiler is offline   Reply With Quote
Old 2010-08-02, 16:27   #7
ET_
Banned
 
ET_'s Avatar
 
"Luigi"
Aug 2002
Team Italia

2·5·479 Posts
Default

Quote:
Originally Posted by mdettweiler View Post
If the computer has integrated graphics available, you could always try running the monitor off that instead of the GPU. AFAIK, that will still leave the computer usable while the GPU is crunching.
I have a motherboard with no integrated video card. It consumes less...

Luigi
ET_ is offline   Reply With Quote
Old 2010-08-02, 16:34   #8
lavalamp
 
lavalamp's Avatar
 
Oct 2007
Manchester, UK

53A16 Posts
Default

Quote:
Originally Posted by ET_ View Post
In 4 months' work we could bring 63 exponents to 80/81 bits...
Ah yes, but have you considered JUST 6 MORE!
lavalamp is offline   Reply With Quote
Old 2010-08-02, 18:49   #9
CRGreathouse
 
CRGreathouse's Avatar
 
Aug 2006

3×1,987 Posts
Default

Quote:
Originally Posted by lavalamp View Post
What do you mean by this?
Has anyone done a theoretical comparison of sieving to that depth vs. searching for small factors by other means?
CRGreathouse is offline   Reply With Quote
Reply

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
How many bits does/did the server trial factor to? Jayder Information & Answers 6 2015-01-25 03:29
Specifing TF factor depth in "Manual Assignments"? kracker PrimeNet 2 2012-07-22 17:49
Current Factor Depth JHagerson Lone Mersenne Hunters 60 2007-06-17 22:35
P95 Trial Factor speeds 40M vs 100M harlee Software 3 2006-10-15 04:38
Shortest time to complete a 2^67 trial factor (no factor) dsouza123 Software 12 2003-08-21 18:38

All times are UTC. The time now is 00:41.

Sat Jan 16 00:41:43 UTC 2021 up 43 days, 20:53, 1 user, load averages: 2.66, 2.88, 2.75

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.