mersenneforum.org  

Go Back   mersenneforum.org > Great Internet Mersenne Prime Search > PrimeNet

Reply
 
Thread Tools
Old 2011-12-29, 23:05   #1
c10ck3r
 
c10ck3r's Avatar
 
Aug 2010
Kansas

547 Posts
Question GPU to 66?

Hello fellow GIMPers!
I've been looking at the GPU272 group's posts and progress, and started to question the idea. I (think I) understand the desire to push the leading and DC waves to higher bit levels in order to potentially reduce the amount of LL needed. I'm sure the effort is worth it to the LLers and DCers, but is it the best use of the GPUs?
So, I would like to tenatively propose a sister project, GPU to 66, with the intention of pushing exponents between 80,000,000 and 1,000,000,000 to 66 bits, leaving the first 80M to the GPU272 crew. This will consist of taking 2,095,083 exponents from 64 to 65 bits, and 20,415,407 exponents from 65-66 bits, minus any no longer needed due to factors in 64-65.
Anybody with me?
Johannes Schuck
c10ck3r is offline   Reply With Quote
Old 2011-12-30, 01:27   #2
petrw1
1976 Toyota Corona years forever!
 
petrw1's Avatar
 
"Wayne"
Nov 2006
Saskatchewan, Canada

10010000111102 Posts
Default

I do not have a GPU to take my comments for what they are worth.

1. The regular TF-LMH will complete the remaining 64-65 bit within a month. And then they will start again at 100,000,000 and go to 66 bits.

2. This will be about a 2-year assignment.....a long time; sort of but not really because it will still be LONG before the LL wave-front will ever get there.

3. I seem to recall reading elsewhere that GPUs preform best at higher bit levels.
petrw1 is offline   Reply With Quote
Old 2011-12-30, 02:15   #3
Dubslow
Basketry That Evening!
 
Dubslow's Avatar
 
"Bunslow the Bold"
Jun 2011
40<A<43 -89<O<-88

3×29×83 Posts
Default

mfakt* design means they're more efficient at longer runs, which in general means lower exponents. But higher exponents also need more TF, so they could be long runs too.

As for your idea, the GPU's are pretty much solely responsible for all TF work between 0 and ~60M, and right now we're not caught up. I think this will happen in the next 3-6 months, i.e. within then I think we'll be ahead of the LL wavefront, at which point your idea is worth more consideration IMO. Also go take a look at the LMH forum; there are some people who use GPU's for TF-LMH, although higher than 100M. There is even a special mfaktc version that is more efficient for the short runtimes.
Dubslow is offline   Reply With Quote
Old 2011-12-30, 02:48   #4
Mini-Geek
Account Deleted
 
Mini-Geek's Avatar
 
"Tim Sorbera"
Aug 2006
San Antonio, TX USA

10AB16 Posts
Default

I think it makes more sense to do a depth-first search (i.e. TF as deep as you can for the LL candidates that will be handed out in the next 0-6 month, while largely ignoring the rest), especially given the relatively new, and therefore likely volatile, nature of the GPU/CPU balance and speeds.
Mini-Geek is offline   Reply With Quote
Old 2011-12-30, 04:15   #5
Xyzzy
 
Xyzzy's Avatar
 
"Mike"
Aug 2002

177518 Posts
Default

In 5 years our GTX5900Ti Extreme "Limited Edition" liquid-nitrogen-cooled GPUs will trial factor all of those in a matter of a few days.

Xyzzy is offline   Reply With Quote
Old 2011-12-30, 05:20   #6
davieddy
 
davieddy's Avatar
 
"Lucan"
Dec 2006
England

2·3·13·83 Posts
Default

Quote:
Originally Posted by Mini-Geek View Post
I think it makes more sense to do a depth-first search (i.e. TF as deep as you can for the LL candidates that will be handed out in the next 0-6 month, while largely ignoring the rest), especially given the relatively new, and therefore likely volatile, nature of the GPU/CPU balance and speeds.
Have I told you lately that I love you?


David
x
davieddy is offline   Reply With Quote
Old 2011-12-30, 15:45   #7
petrw1
1976 Toyota Corona years forever!
 
petrw1's Avatar
 
"Wayne"
Nov 2006
Saskatchewan, Canada

121E16 Posts
Default

Quote:
Originally Posted by Mini-Geek View Post
I think it makes more sense to do a depth-first search (i.e. TF as deep as you can for the LL candidates that will be handed out in the next 0-6 month, while largely ignoring the rest), especially given the relatively new, and therefore likely volatile, nature of the GPU/CPU balance and speeds.
Isn't that what George started a few months ago when he added 2 or 3 more bit levels in the 50M range?

Or are you proposing more bits yet?
petrw1 is offline   Reply With Quote
Old 2011-12-30, 17:16   #8
davieddy
 
davieddy's Avatar
 
"Lucan"
Dec 2006
England

2×3×13×83 Posts
Default

Quote:
Originally Posted by petrw1 View Post
Isn't that what George started a few months ago when he added 2 or 3 more bit levels in the 50M range?

Or are you proposing more bits yet?
Yep.
Unfortunately the ~26,000 primenet TF assignments have ground to a halt at 71 bits. The optimal bit level is still governed by the GPU firepower available ATM, but the times they are a changin'.

David
davieddy is offline   Reply With Quote
Old 2011-12-30, 19:11   #9
garo
 
garo's Avatar
 
Aug 2002
Termonfeckin, IE

22×691 Posts
Default

@OP
Bad idea. If you factor all these exponents to higher levels, slower CPUs will not be able to contribute meaningfully to GIMPS. It will be a long long time before even 100M exponents are handed out for LL tests so we need to concentrate on the immediate job first. Make sure every exponent under 60M due to be handed out for LL is factored to 71/72/73 bits.
garo is offline   Reply With Quote
Old 2012-01-02, 18:38   #10
davieddy
 
davieddy's Avatar
 
"Lucan"
Dec 2006
England

2×3×13×83 Posts
Default

Sounds like Garo half agrees with me (albeit loathe to admit it).
The brutal fact is that CPUs have been rendered redundant for any TF.
If the fast guys would let up a bit on DCs (do the man-sized LL work instead), slower CPUs can do them. If the DC wavefront were smaller (say 1/3) than the LL wavefront, the chance of finding a prime per GHzDay would become comparable to that of first time LLs.

David

Last fiddled with by davieddy on 2012-01-02 at 18:39
davieddy is offline   Reply With Quote
Old 2012-01-02, 18:45   #11
Dubslow
Basketry That Evening!
 
Dubslow's Avatar
 
"Bunslow the Bold"
Jun 2011
40<A<43 -89<O<-88

3×29×83 Posts
Default

What do you mean by 'smaller'? I personally put one core to P-1, one to LL, one to DC, and one to mfaktc. That way by numbers I get the most P-1, second most DC, and least LL, while maintaining the same 'GHz-Days' throughput. Unless the DC throughput rate matches the LL throughput rate, I will continue to keep at least one core on DC.

Also, most of us agree in general with garo, and by proxy with you. You just keep spouting off anyways. (We're giving it all she's got, captain!)
Dubslow is offline   Reply With Quote
Reply

Thread Tools


All times are UTC. The time now is 13:04.

Tue May 18 13:04:06 UTC 2021 up 40 days, 7:44, 1 user, load averages: 2.35, 1.98, 1.89

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.