Thread: 2^1466L done
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Old 2006-02-28, 15:06   #2
Wacky's Avatar
Jun 2003
The Texas Hill Country

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Really finishing 2,1146L ...
Somebody entered incorrect data for the sieving effort parameters. We are really only about half done.

We are considering doing 2,797+.c150 which is what is left thanks to Bruce finding a 55 digit factor by ECM. This is now in the range where GNFS is more efficient that using the original SNFS polynomials.

However, there is one potential problem for our participants.
The typical SNFS project has something like 40M "lines" where each line is perhaps 90M long. This allows us to make assignments where the atomic assignment takes only a fraction of a minute and each client processes hundreds of them in a single task.

But with the GNFS polynomials, the sieving area is not so square.
Here we need perhaps only 250K lines, but each line is 18.9G long.
The difficulty is that the atomic assignment will now require perhaps 10 minutes, and we have no reasonable way to provide a finer granularity.

For many of the sievers, this is no problem. They sit there and sieve 24/7 at the lowest priority. So, they don't even notice that the OS may have suspended them while something of higher priority was run.

However, we also have another class of participants who frequently start and stop the siever in order to reboot or otherwise use the machine resources. Those users are often willing to wait a few seconds for the siever to stop gracefully. But asking them to wait a number of minutes would not be appropriate.

The best suggestion that I have at the moment is to sieve two projects simultaneously. Those who can process the longer assignments could work on 2,797+ while the others begin another SNFS project.



Last fiddled with by Wacky on 2006-02-28 at 15:07
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