20111108, 07:17  #1 
Jun 2010
Pennsylvania
1110100110_{2} Posts 
Whither TF?
Taking a quick break from the rigors of the publishing industry. I have an observation, and a question based on it.
One of my computers is assigned to do TF. When it started crunching some 15 months ago, it was getting exponents in the low 100M range. Now, some 15 months later, it's receiving exponents north of 320M. Obviously, the advent of GPU computing has had an effect. At this rate (which no doubt will continue to increase), trial factoring will hit OBD territory sometime in 2015. When that happens, how will the TF portion of GIMPS proceed  will it move into billiondigit exponents; recap previous exponents at deeper bit levels; or something else? Just curious. Rodrigo Last fiddled with by Rodrigo on 20111108 at 07:19 
20111108, 07:40  #2  
"Lucan"
Dec 2006
England
2×3×13×83 Posts 
My 2p worth
Quote:
find something else to do. And since it takes as long to TF from X to X+1 bits as it does from 0 to X, all work above 60M is of neglible value as far as GIMPS is concerned. David Last fiddled with by davieddy on 20111108 at 07:43 

20111108, 08:02  #3  
Jun 2003
2·3·827 Posts 
Quote:
Quote:


20111108, 09:35  #4 
"Nathan"
Jul 2008
Maryland, USA
5×223 Posts 
You might remember this is what happened after we ran out of 63>64 bit assignments in August 2010. Once we finish TFing everything to 65, the LMH assignments will likely start over again at 100M, this time TFing to 66. Note that this will take twice as long as the effort from 64 to 65. So if it takes, say, 18 months (August 2010  February 2012) to finish everything to 65 bits, we will be busy for three years (!) with finishing everything to 66 bits. When you also consider that the ninefigure exponents all need to be TFed to at least 72, we will certainly be busy for the foreseeable future, even with the lumberjacks and the GPUs.

20111108, 09:38  #5 
Einyen
Dec 2003
Denmark
31×101 Posts 
It's better to keep TF exponents below 1 billion to higher bit ranges instead of moving beyond 1 billion, since LL wavefront probably won't get there in our lifetimes unless some major advances in algorithm or quantum computing.

20111108, 09:45  #6 
"Nathan"
Jul 2008
Maryland, USA
10001011011_{2} Posts 
Once I jump the broom into the Great Beyond(TM), I plan on picking up right where I left off. First thing is to talk the angel processing new arrivals into letting me install Prime95 on her quantum computer.
(And she'll say, "But, sir, I already have it testing MMMM127!". Or, everyone will start laughing, as I get handed a paper containing a 2line proof that there are no Mersenne primes above 2^60,000,0001.) 
20111108, 16:52  #7  
Jun 2010
Pennsylvania
2·467 Posts 
Quote:
So higher bit levels it is. Thanks, guys! Rodrigo 

20111108, 20:43  #8  
Jun 2010
Pennsylvania
1646_{8} Posts 
Quote:
The monthtomonth jump in the size of the TF exponents my computer is completing (recently assigned), has grown from 12.4M (10/8/10  11/8/10) to 24.2M (10/8/11  11/8/11). This was not a fluke: the jump in the period 9/8/10  10/8/10 was 9.7M, while the jump in the period 9/8/11  10/8/11 was 20.7M. Here are the monthly jumps (every month on day 8): Date  Exponent  Difference 11/10 1259xxxxx 12/10 1383xxxxx +124xxxxx 01/11 1478xxxxx +095xxxxx 02/11 1614xxxxx +136xxxxx 03/11 1737xxxxx +123xxxxx 04/11 1862xxxxx +125xxxxx 05/11 2022xxxxx +160xxxxx 06/11 2193xxxxx +171xxxxx 07/11 2369xxxxx +176xxxxx 08/11 2549xxxxx +180xxxxx 09/11 2739xxxxx +180xxxxx 10/11 2944xxxxx +205xxxxx 11/11 3186xxxxx +242xxxxx So the monthtomonth jumps were rather flat from 11/10 to 4/11, and since then they've been rising at an increasing pace. Help me to understand. Are there that many more CPUs doing TF this fall, than there were last fall? What happened in April/May of this year, to account for the sudden (and growing) jump in the rate of increase? Are certain ranges being skipped? Please note  I'm not being contentious, just trying to get a handle on how this works. Thanks! Rodrigo 

20111108, 20:57  #9  
If I May
"Chris Halsall"
Sep 2002
Barbados
2·4,787 Posts 
Quote:
Quote:
Quote:
It's in our nature.... 

20111108, 21:05  #10 
Oct 2011
7·97 Posts 

20111108, 21:15  #11 
If I May
"Chris Halsall"
Sep 2002
Barbados
2·4,787 Posts 
Thanks for the correction. You (and Rodrigo) are correct  I misread it.
Last fiddled with by chalsall on 20111108 at 21:26 Reason: added "(and Rodrigo)" 