mersenneforum.org 5^421-1 sieving (reservations closed)
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 2008-07-21, 17:30 #1 fivemack (loop (#_fork))     Feb 2006 Cambridge, England 2·7·461 Posts 5^421-1 sieving (reservations closed) The .poly file is Code: n: 856747567165509732120757534754047466186338557004916269612235956443230634437193149247989845404816349224130750819510131856088353227722964229252203600736528648205287332264407802189199 skew: 1287906.31 c5: 5767280580 c4: -12525357190853198 c3: -23832471548163085528052 c2: 16917954271985164657592650551 c1: 14831413561315809659995278076458170 c0: -5682335232801110703624206006414844672400 Y1: 46531574816134967669 Y0: -10823715308709192191932199683059669 lpbr: 31 lpba: 32 mfbr: 62 mfba: 64 rlambda: 2.6 alambda: 2.6 rlim: 80000000 alim: 150000000 The rational-side yield is much lower than the algebraic-side yield, so I think it makes sense to sieve on the algebraic side only. 31-bit rational primes give something like 40% more relations per Q and need about 20% more relations than 30-bit rational primes would; the R and A factor-base limits are about right. A million-Q range should take about ten CPU-days to sieve (using the 64-bit ggnfs executable on a Core2/2400) and produce a bit over a million relations; we want about 400 million, so there's lots of reservation space. Use ggnfs-lasieve4I15e; the jobs take about ten minutes to get started, and use 900M of virtual and 400M of physical memory (450M under Windows). (12 Sep 2008)Please make reservations in the 40M-80M region before carrying on from 328M (24 Sep 2008) Not taking any more reservations; this lot should suffice! Reservations Code: bsquared 40M-53M (done 30/09) batalov 53M-55M (done 27/09) bsquared 55M-75M (done 25/09) fivemack 75M-90M (done 26/09) smh 90M-100M fivemack 100M-120M (done 14/09) smh 120M-124M (done 07/09) fivemack 124M-130M (done 02/09) smh 130M-136M (done 31/08) andi47 136M-140M smh 140M-145M (done 07/08) frmky 145M-150M (done 02/08) fivemack 150M-162M (done 02/08) FactorEyes 162M-170M (done 12/09) andi47 170.03M-172.27M (done 01/09) fivemack 172.27M-174M (done 13/09) Batalov 174M-180M (done 19/09) bsquared 180M-200M (done 31/07) bsquared 200M-220M (done 08/08) fivemack 220M-236M (done 18/08) bsquared 236M-256M (done 18/08) fivemack 256M-268M (done 30/08) bsquared 268M-288M (done 27/08) bsquared 288M-308M (done 10/09) bsquared 308M-328M (done 19/09) bsquared 328M-338M (done 24/09) fivemack 338M-340M (done 29/09) Ranges that I have Code: 40M-92M 100M-136M 140M-340M Last fiddled with by fivemack on 2008-10-01 at 10:52 Reason: Reservations Update
2008-07-21, 19:20   #2
jasonp
Tribal Bullet

Oct 2004

32·5·79 Posts

Quote:
 Originally Posted by fivemack A million-Q range should take about ten CPU-days to sieve and produce a bit over a million relations; we want about 400 million, so there's lots of reservation space
With these parameters, your job will be the first test of msieve with 32-bit large primes. The entire library is supposedly '32-bit clean', but I expect postprocessing trouble commensurate with the epic size of this job. Did your 8G machine ever run the lanczos solver reliably?

Last fiddled with by jasonp on 2008-07-21 at 19:21

 2008-07-21, 21:36 #3 fivemack (loop (#_fork))     Feb 2006 Cambridge, England 645410 Posts I managed to run a small job (29-bit large primes) to completion with four threads on that 8G machine at one point, but I've had no luck getting the machine to misbehave on anything other than msieve, or reliably enough to be diagnosed when running msieve. So I'm contemplating getting another machine; I've got the money in the bank, but I'll wait until the sieving has finished in the hope that Nehalem exists by then. [there's a 16GB 8-core Penryn machine at work, but it's the fileserver, and running jobs that use most of it for months will not make me popular]
2008-07-22, 04:33   #4
Andi47

Oct 2004
Austria

2×17×73 Posts
Nehalem

Quote:
 Originally Posted by fivemack So I'm contemplating getting another machine; I've got the money in the bank, but I'll wait until the sieving has finished in the hope that Nehalem exists by then. [there's a 16GB 8-core Penryn machine at work, but it's the fileserver, and running jobs that use most of it for months will not make me popular]
Hmmm... The Nehalem - Lynnfield processor has been postponed from Q1 2009 to Q3 2009 since I looked the last time (a few months ago). The Bloomfield processor (more powerful but it consumes more energy - 130 W) is due at Oct. 2008.

Edit: For a longer-term test (a few days up to a few weeks) on your big machine you can possibly double-check M100,000,007 using prime95 version 25.6 (multithreaded). There are several interim residues posted in this thread, beginning at ~iteration #12M, and further every few million iterations.

Last fiddled with by Andi47 on 2008-07-22 at 04:45

2008-07-22, 09:38   #5
Andi47

Oct 2004
Austria

2·17·73 Posts

Quote:
 Originally Posted by fivemack Use gnfs-lasieve4I15e; the jobs take about ten minutes to get started, and use 900M of virtual and 400M of physical memory.
in windows it takes ~450MB of physical memory.

 2008-07-23, 00:00 #6 FactorEyes     Oct 2006 vomit_frame_pointer 23·32·5 Posts How long for the seiving on this one? If we assume that 11 volunteer sievers step up with an average of 36 million Q values apiece, that's 1 core-year (=360 core-days) per volunteer, to get the sieving done. I'm assuming all have the 64-bit optimized 4I5e running, which is optimistic. At 4 cores per volunteer, that's 3 months' running time. Obviously there are the odd free cycles from clusters, which will likely do 1/3 of the work, so we're down to, say, 2 solid months from each volunteer with 4 cores available. Over the next 45 days I can easily finish my commitment of 8 million Q values, and I'll toss in more if they're needed, but I doubt I could sieve more than 20 million Q in six months. Give me a year, and I could toss in at least 30 million. It seems as if 4-5 months of sieving is the bare minimum here, unless there is substantial enthusiasm for this project. I think it's worth doing, especially since the linear algebra will push things a bit. I'm trying to get an idea of how to prioritize my current stack of fun integers. Do my ideas about the timeline sound about right?
2008-07-23, 07:38   #7
fivemack
(loop (#_fork))

Feb 2006
Cambridge, England

2·7·461 Posts

Quote:
 Originally Posted by FactorEyes If we assume that 11 volunteer sievers step up with an average of 36 million Q values apiece, that's 1 core-year (=360 core-days) per volunteer, to get the sieving done. I'm assuming all have the 64-bit optimized 4I5e running, which is optimistic. At 4 cores per volunteer, that's 3 months' running time. Obviously there are the odd free cycles from clusters, which will likely do 1/3 of the work, so we're down to, say, 2 solid months from each volunteer with 4 cores available.
That's much the same timescale that I was anticipating, though I suspect the average cores per volunteer is probably a bit over four given that there are people who sieve using idle cycles at work. I wouldn't recommend anyone making a reservation now that takes more than about six weeks to finish; I've spoken for a million per available core and will get another million per core as and when those finish, I think that's about the right strategy though obviously it's worth reserving more if you know you want the machine to run unattended over a summer vacation.

Quote:
 It seems as if 4-5 months of sieving is the bare minimum here, unless there is substantial enthusiasm for this project. I think it's worth doing, especially since the linear algebra will push things a bit.
There seems to be reasonable enthusiasm - bsquared has a lot of compute resources, and it's only been 36 hours since I put the message up - though the people with the enormous clusters are committed to a long list of large SNFS jobs.

2008-07-23, 10:10   #8
Andi47

Oct 2004
Austria

2·17·73 Posts

Quote:
 Originally Posted by fivemack ...obviously it's worth reserving more if you know you want the machine to run unattended over a summer vacation.
That's exactly what I do: I will be on summer vacation the whole august, and so I reserved a range which should be finished near the end of august / beginning of september. (I hope it's ok when I don't finish before the 1st week of september)

Shortly before I leave for vacation I will reserve a second range (for the second thread of the core2duo). I can't start this right now, because it would take ~90-92% of the available memory and thus will make it nearly impossible to work at this computer.

 2008-07-23, 19:41 #9 bsquared     "Ben" Feb 2007 1110100101002 Posts To be fair, I personally have very small compute resources; one lowly Athlon 4200+ X2 to be precise. The compute resources I have *access* to are quite a bit more substantial. Which reminds me that I'd like to make sure Sam Wagstaff is informed of that fact so the various universities can be acknowledged in the cunningham book. Hopefully that's possible. I'm also grateful to Tom for organizing efforts like these, otherwise said resouces would be woefully underutilized. I can manage to launch a few scripts to aid projects which have already been skillfully researched and organized but a 3 year old and a 5 month old tend to otherwise occupy any time not spent working or sleeping :) Looking forward to seeing this one through! - ben.
2008-07-26, 04:43   #10
Batalov

"Serge"
Mar 2008
Phi(4,2^7658614+1)/2

89·113 Posts

Quote:
 Originally Posted by fivemack A million-Q range should take about ten CPU-days to sieve (using the 64-bit ggnfs executable on a Core2/2400) and produce a bit over a million relations
I get about 1.36M rels from my interval (I guess you are counting the future non-redundant rels).
The file will be about 150Mb in size, and after "bzip2 -9", 72Mb.
Please remind where we should upload them and what's the secret city this time.

Serge

 2008-07-26, 20:45 #11 fivemack (loop (#_fork))     Feb 2006 Cambridge, England 2·7·461 Posts Code: ftp chiark.greenend.org.uk user: anonymous pass: your email address cd special/twomack-relations/malmo put 150M-151M.bz2 I have moved across the Oresund from Denmark to Sweden for my secret city this time.

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