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Old 2007-10-22, 02:09   #43
gd_barnes
 
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May 2007
Kansas; USA

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Default Great thoughts Curtis!

Quote:
Originally Posted by VBCurtis View Post
There is no other k sieved so deeply below 1M, because no other k had a single sieve done to 4M. Efficiency increases greatly with a larger n-range; combined with empirical evidence that removing the small n's provide very little speed benefit to the overall sieve, it makes sense to sieve extremely deeply for large sieves. Sheep's farm(s) have sieved k=15, my group of k's (11,13,31,45,99,127, and now 5), rieselsieve, and some other stuff I'm forgetting. PowerPCs have no LLR client, alas.

The 14 k's drive has quite a lot of life left for LLR before we need a new team drive; quite a few users prefer to do everything themselves (me included). I think building a new team drive with a dozen or so k's is a great idea, using Sheep to sieve; however, moving 100+ k's to a group effort puts global efficiency above individualism. A possible compromise is to build such a global sieve, but continue to allow users to reserve entire k's out of the sieve, rather than team LLR everything. Those who like to sieve (or have athlons or laptops that aren't well suited to LLR) can reserve ranges from this massive sieve. If we ever do this, we should still leave some k's untouched for those interested to process entirely on their own. Perhaps put 30 k's of various weights into a mass sieve... eventually.

Another way to look at this is max efficiency comes from the largest n-range, but we do not usually sieve very-large n-ranges. Why not? The same long-run "greater good" is achieved by sieving a range twice as high as sieving twice as many k-values. One chooses limits on both for practical, project-completion reasons. Only for very large n-ranges does one not need to finish sieving for max efficiency before starting LLR; if sieving 100 k's, that sieving step would be many CPU-years. And what about file size? The sieve needs to be practically emailed, which puts a 10MB or 20MB limit.

I tried 33 k's from 260k to 300k, in the 900-1000 range (see primesearch), as an experiment. It was NOT efficient. Many k's with a narrow n range is bad bad bad for sr1/sr2. Big fat n ranges are incredibly efficient. Thus, my decision to run this k=5 sieve to 4M, and the resulting ~100T sieve depth for n<1M.
-Curtis
A lot of great points, Curtis. I agree somewhere closer to along the lines of what you suggested more than my own about the 'huge' sieve or 'team drive'...put 30 k's into some big mass sieve and sieve all of them up to about n=3M-4M or so. It could be called a 'drive' or whatever we want. The main point that is good about what you mentioned is to have some massive sieved files out there for a whole bunch of different k's and just let people reserve the k's and grab the ranges of the sieved files that they want. That would be cool! And if people only wanted to (or only could) sieve instead, they could just sieve on this massive file if they wanted to or add additional ranges of n at the high-end of the sieve file or something of that nature. Or if they wanted to do a k all by themselves, then leaving a number of them untouched and not sieved at all would fill the bill there.

Obviously the more k's sieved at once, the more efficient for the 'long-term good'. There's certainly nothing wrong with sieving 100's of k's at once but you're right, removing individualism would remove some of the fun, myself included. As I mentioned, you'd definitely want to sieve up to n=2M-3M. As you said, sieving a small range of n is highly inefficent and not worth doing.

Back on sieving k=5...I'm not debating your mathematics about when to split off the ranges to LLR. But I'm not so sure I agree with continuing to sieve so long on an effort like this for k=5 even though we've included the huge range of n=470K-4M in the sieve. The point here is about economics, that is good old supply and demand. We have a really big supply of LLRers ready to go.

My opinion...release every range that everyone has already reserved by 10/31. (Obviously earlier for Carlos.) (Also, my 630-660 will be done Wednesday and I could start on 740-760 Thursday if you release it.) It doesn't matter whether it's sieved to 58M or 60M or 120M or whatever, I'd still say just release the reserved ranges and keep sieving the rest. As people are ready for their next range, just send it to them regardless of how far sieved up to at least n=1M at this point. 60M is very sufficient for this effort to n=1M. That gives us the greatest chance to have everything LLR'd to n=1M by the end of 2007.

My reasoning has to do with 'elastic supply' in this case. That is, if you release things as fast as people are ready for them, other people may come into the picture. For instance, Kosmaj, Karsten, Lsoule, Amphoria, etc. may pick up a couple of ranges to LLR also. People love this fast LLRing low k.


Gary

Last fiddled with by gd_barnes on 2007-10-22 at 02:10
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