Help needed for doublecheck sieving!

[em99010pepe]

Originally Posted by gd_barnes

My bad here. Now I need to go back and look at how far I should have sieved 400<k<=1001 for n=260K-1M using the new version of sr2sieve. If it is worth it, I may sieve n=400K-600K to P=6T. But with only a 200K n-range, it may not be worth it.

I think you should sieve.

[gd_barnes]

Originally Posted by em99010pepe

I think you should sieve.

In this effort or on the n=400K-600K range?

[em99010pepe]

Originally Posted by gd_barnes

In this effort or on the n=400K-600K range?

On the n=400K-600K range, LLRnet is already with work until 370k.

[mdettweiler]

Originally Posted by em99010pepe

On the n=400K-600K range, LLRnet is already with work until 370k.

The only problem is...last I heard, all of Gary's machines are busy sieving 300<k<400. So he would have to get some power from elsewhere, or steal it from 300<k<400, if he was going to sieve n=400K-600K further.

We could, as an alternative, make it a public sieve effort, like this one.

[gd_barnes]

Originally Posted by Anonymous

The only problem is...last I heard, all of Gary's machines are busy sieving 300<k<400. So he would have to get some power from elsewhere, or steal it from 300<k<400, if he was going to sieve n=400K-600K further.

We could, as an alternative, make it a public sieve effort, like this one.

I'll do some analysis on removal rate for the narrower n=400K-600K range using sr2sieve during the day Tues.

I think it would have been worth it for for n=260K-600K but I'm not so sure for n=400K-600K. Once the LLR time has been expended for a large portion of a range, it becomes less beneficial to sieve the remaining range. I'll let you know.

Done in by improving software... lol


Gary

[mdettweiler]

120G-130G complete.

[gd_barnes]

Originally Posted by em99010pepe

On the n=400K-600K range, LLRnet is already with work until 370k.

I redid some analysis I did back when I was sieving 400<k<=1001 for n=260K-600K using sr2sieve:

Machine used for both LLR and sieving test: 1.66 Ghz Dell core duo
(about equally good at sieving and LLRing)

70% n-range = 498K
Candidate chosen for LLR test:
693*2^498000-1
Time per iteration: .835 ms
Iterations: 498K
Total LLRing time: 416 secs.

Sieving test on n=260K-600K for 400<k<=1001:

Way back when, srsieve was faster. I was getting P=67K/sec. and confirmed that with a recent test.

I just now ran a test using the new version of sr2sieve. It was at P=88K/sec. :surprised Yep, it's faster now. (Previously ~P=50K/sec. if I remember right.)

Analysis sieve: P=5000G-5010G:
Expected factors found: 271 (much more accurate than actual found)
P-rate/sec. using srsieve: 67K/sec.
Est. seconds to process P=10G: 10G / 67K = 149254
Est secs. per factor found: 149254 / 271 = 551

The 551 sec. removal rate vs. 416 sec. LLR time confirms that I initially over-sieved the range. My original analysis showed an optimal depth of P=4.25T-4.5T but I wanted it to be 10-15% over-sieved since most everyone else would be LLRing.

Now, going back and using sr2sieve instead on the entire range:

Analysis sieve: P=5000G-5010G:
Expected factors found: 271
P-rate/sec. using srsieve: 88K/sec.
Seconds to process P=10G: 10G / 88K = 113636
Secs. per factor found: 113636 / 271 = 419

surprised:surprised

Now, how LUCKY is that? Had I used sr2sieve originally, P=5T is almost exactly the right depth for the range: 419 secs. removal rate vs. 416 secs. LLR rate.

Therefore sieving the smaller range of n=400K-600K would be foolish. With only 200K/340K (58.8%) of the n-range, the removal rate would be 419 secs. / .588 = 712 secs. A 70% n-range candidate of n=540K wouldn't take nearly that long to LLR.

Conclusion: No additional sieving needed for 400<k<=1001.

Future: Thanks to sr2sieve, I'm sieving 300<k<400 to P=6T, which will save additional LLRing time.

Thanks to Geoff for the nice increase in sr2sieve sieving speed!


Gary

[Flatlander]

80G-120G complete.

[mdettweiler]

New sieve file released, sieved to p=130G.

[mdettweiler]

Hi all,

We've decided to include k<300 (for the same n-range, 100K-260K) in this doublecheck sieving, since it's currently doublechecked up to n=100K, just like the 300<k<1001 range. Chris (Flatlander) and I started the sieving for k<300 and caught it up to the 300<k<1001 sieve, and I've now combined the two sieve files into one. Please make sure you download the new sieve file before starting on any new (i.e. past 130G) reservations.

The new sieve file contains a total of 500 k's, and thus a given range will take a little longer (probably about 25% longer, I'm guessing--though that's not much more than a guess; please feel free to post information on what speeds you're getting with the new sieve file). As we had agreed before for 300<k<1001, we'll be taking the whole thing up to 1T (though when we reach 200G Gary will do another analysis, to confirm that estimate). (For the uninitiated, 1T=1000G. )

Have fun!

Anon

[gd_barnes]

Originally Posted by Anonymous

Hi all,

We've decided to include k<300 (for the same n-range, 100K-260K) in this doublecheck sieving, since it's currently doublechecked up to n=100K, just like the 300<k<1001 range. Chris (Flatlander) and I started the sieving for k<300 and caught it up to the 300<k<1001 sieve, and I've now combined the two sieve files into one. Please make sure you download the new sieve file before starting on any new (i.e. past 130G) reservations.

The new sieve file contains a total of 500 k's, and thus a given range will take a little longer (probably about 25% longer, I'm guessing--though that's not much more than a guess; please feel free to post information on what speeds you're getting with the new sieve file). As we had agreed before for 300<k<1001, we'll be taking the whole thing up to 1T (though when we reach 200G Gary will do another analysis, to confirm that estimate). (For the uninitiated, 1T=1000G. )

Have fun!

Anon

In theory, since the rate of sieving varies by the square root of the # of k's, it should sieve sqrt (500/351)-1 = ~19.4% slower. But it will find more factors / P-range.

With the efficiency of more k's, sieve depth should increase slightly. After I said it, 1T seemed a little high but it might be real close with 500 vs. 351 k's. It's very unusual to sieve to 1T for a non-top 5000 range but then again, it's very unusual to sieve 500 k's at once too!


G