3,637- has been factored into 85-digit and 127-digit prime numbers. In other news, the National Science Foundation XSEDE grant has been renewed for another year, so we have lots of sieving to do! We can use as much computing time as you have available to donate, and your help is greatly appreciated!
/ 
Reply
Quote
It's pretty good news that the grant was renewed :)
/ Reply
Quote
It's pretty good news that the grant was renewed :)
Agree.
Carlos
/ Reply
Quote
Great to hear. Dose the grant give you x amount of computer time post processing?
/ Reply
Quote
Exactly. For this year, we receive a little over 1 million CPU-hours for postprocessing.
/ Reply
Quote
Gr8 news. That's just over 167 years of CPU time. Out of interest how much work is done in an hour of postprocessing time?
/ Reply
Quote
based on my calculation, TAOCP need 11114,893 hours to do the post-processing on 1 Core 2 Quad core
/ Reply
Quote
Why do you have the 1000th comment Greg?
/ Reply
Quote
The amount of time required for postprocessing depends on the number. The recently completed largest number so far, 2,1061+, required about 340,000 core-hours to postprocess. I ran the code using 576 cores, so it required about 3.5 weeks of actual calculation time to complete.
I got the 1000th post simply by luck! That was not planned. :)
/ Reply
Quote
Thanks Greg. Man post processing takes along time. How many cores do you have to run on one job & whats the most core you've used at one time?
/ Reply
Quote
Thanks Greg. Man post processing takes along time. How many cores do you have to run on one job & whats the most core you've used at one time?
Here you have my timings for lasieved numbers for post-processing using a core i5 750@3.4 GHz:
/ Reply
Quote
Thanks for the chart.
/ Reply
Quote
Please don't take into consideration last column, named Total Time. I was just trying to figure how much BOINC points were equivalent for the sum of all post-processing phases. All numbers are in seconds.
Example, post processing of 5_492_plus1 took:
Filtering - 1 core - 3.300 seconds
Linear Algebra - 4 cores - 258.780 seconds
Square Root - 1 core - 1.234 seconds
So overall it took me 263.314 seconds (~73 hours) on my machine to do the post-processing of 5_492_plus1.
/ Reply
Quote
How many cores do you have to run on one job & whats the most core you've used at one time?
For the large numbers, I use the TACC Lonestar and SDSC Trestles clusters. Lonestar has over 20,000 cores and Trestles has over 10,000 cores. However, as you use more cores the calculation becomes less efficient. The largest I have run is 900 cores, but I typically use 576 cores in a 24 x 24 grid.
/ Reply
Quote
Thanks for the great answers. Greg have you been tempted to Sieve a job on 576? I bet it would be done fast.
/ Reply
Quote
Right now, NFS@Home has the rough equivalent of ~1000 cores running full time, so adding 576 cores would only reduce the overall sieve time by about 1/3.
/ Reply
Quote
Right now, NFS@Home has the rough equivalent of ~1000 cores running full time, so adding 576 cores would only reduce the overall sieve time by about 1/3.
Fair enough. I wasn't very clear. What I meant was if you could run 1 task on 576 cores it would be done in no time.
/ Reply
Quote