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 2009-09-09, 23:52 #1 fivemack (loop (#_fork))     Feb 2006 Cambridge, England 11000101100112 Posts A computation worthy of the name I have spent a little while figuring out parameter choice for this; here is the polynomial for 2^941 - 1: Code: n: 2468815427808777830385945175570959888649322954010151512577652841207233127175594988619285951813249353482864131674513502872982111245757912252275917421142241044267118542381889815949472721865947896251559297022100274282885756253947868389157090816092206938192397903861973556952725044519 c6: 1 c0: -2 Y0: 182687704666362864775460604089535377456991567872 Y1: 1 skew: 1.12 rlim: 300000000 alim: 250000000 lpbr: 32 lpba: 32 mfbr: 64 mfba: 64 rlambda: 2.6 alambda: 2.6 We will need about six hundred million raw relations, which I propose to get by sieving with -16e from Q=50 million to somewhere a little past Q=200 million on both sides. I have done 0.005% of the job (1k in each 20M) on a quad-core 2.4GHz Core 2 running 64-bit Linux, with 8G of memory and 16G of swap; it took from 8:30pm to half past midnight, and used no swap space. Each CPU-minute produces about forty relations; fifteen million minutes is thirty years. This job would take a day even on one of the pride-of-the-National-Labs supercomputers; I'll need all the help I can cajole. The final parts of the job will take me about a season on a reasonably fast Core i7 system. RESERVATIONS CLOSED 24/11 RESERVATIONS 10/9 andi47 50-51 A+R (A side done 30/10, R side partially handed over to fivemack and done 13/11) 10/9 bsquared 51-61 A+R done 29/9 10/9 fivemack 61-67 A+R done 25/10 (slowed by uploading issues) 10/9 batalov 67-69 A+R done 29/9 01/10 bsquared 69-74 A+R done 11/10 13/10 J.F. 74-75 A+R done 22/11 13/10 bsquared 75-80 A+R done 26/10 15/10 fivemack 80-86 A+R done 13/11 22/10 frmky pp NFS@home 86-90 A+R done 11/11 24/10 frmky pp NFS@home 90-100 A+R done 11/11 30/10 bsquared 100-102 A+R done 06/11 08/11 fivemack 102-107 A+R done 24/11 13/11 bsquared 107-110 A+R 97.5%-done 19/11, finished 23/11 10/9 bdodson 110-190 A+R done 20/11 17/11 bdodson 190-200 A+R 16/11 NFS@home 200-225R RESULTS 18/09 batalov 67-68R 2,122,258r in 2.0Msec PhenomII/3000 22/09 batalov 67-68A 2,156,943r in 2.0Msec PhenomII/3000 25/09 fivemack 61-62A+R 4,340,480r in 5.3Msec various systems 26/09 batalov 68-69A 2,137,457r in 2.0Msec PhenomII/3000 29/09 batalov 68-69R 2,118,321r (presumably in 2.0Msec PhenomII/3000) 29/09 bsquared 51-61A+R; 43,716,577r in 61.1Msec k8/2000. 06/10 fivemack 64-65A+R; 4,300,156r in 5.6Mtsec on eight threads of i7@2800MHz 11/10 bsquared 69-74A+R; 21,206,954r in 31.2Msec k8/2000 (ran filtering job) 13/10 fivemack 63-64A+R; 4,307,838r in 5.0Msec various systems 13/10 fivemack 62-63A+R; 4,313,909r in 4.9Msec C2/2400 15/10 fivemack 65-66A+R; 4,309,003r in 5.6Mtsec on eight threads of i7@2800MHz 25/10 fivemack 81-82A+R; 4,172,590r in 2.45Msec K10/2500 + 2.64Msec C2/2400 25/10 fivemack 66-67A+R; 4,296,209r in 5.05Msec various systems 26/10 bsquared 75-80A+R; 20,068,462 relations in 30.6Msec k8/2000 27/10 bdodson 110-150R; 78,785,145 relations 28/10 fivemack 80-81A; 2077128 relations in 2.7Msec various systems 28/10 bdodson 150-170R; 37,937,272 relations (ran filtering job) 30/10 andi47 50-51A; 2,265,218 relations 02/11 fivemack 80-81R; 2,095,566 relations in 3.1Msec various systems 02/11 fivemack 82-83A+R; 4,162,666 relations in (a)2.56Msec K10/2500 + (r)2.45Msec C2/2400 04/11 fivemack 83-84A+R; 4,149,546 relations in (a)2.82Mtsec i7/2800 + (r)2.76Mtsec i7/2800 - 241 hours realtime 06/11 bsquared 100-102A+R; 8,076,444 relations 06/11 bdodson 170-190R; 35,163,889 relations 06/11 bdodson 110-130A; 38,603,445 relations 10/11 fivemack 84-85A: 2,062,050 relations in 2.84Msec various systems 10/11 fivemack 84-85R: 2,074,375 relations in 2.43Msec K10/2500 11/11 nfs@home 86-100R: 28,995,972 relations 11/11 nfs@home 86-100A: 28,868,800 relations 13/11 fivemack 85-86A+R; 4,155,760 relations in (a)2.86Mtsec i7/2800 + (r)2.77Mtsec i7/2800 - 204 hours realtime (ran filtering job: 35.3 megacycles) 13/11 andi47 50-50.2R + fivemack 50.2-51R; 2,153,725 relations 13/11 bdodson 130-170A: 72,248,902 relations (ran filtering job; 28.1M matrix) 17/11 fivemack 102-103A+R: (a) 2,001,779rel in 2.55Msec C2/2400 (r) 2,038,855rel in 2.47Msec K10/2500 18/11 fivemack 104-105A+R: (a) 1,981,674rel (r) 2,030,985rel (various systems) 19/11 bsquared 107-110A+R (97.5% done) 11,709,149 rel; last relations collected 23/11 20/11 bdodson 170-190A: 35,387,263 rel 22/11 fivemack 103-104A+R: (a) 1,988,386rel in 2.82Mtsec i7/2800 + (r) 2,034,560 rel in 2.78Msec i7/2800 - 204 hours realtime 22/11 J.F. 74-75A+R: 4,197,092 rel, 5.02Msec runtime 23/11 bdodson 190-200R + patches from 160A and 180R: 18,329,135 + 1,328,828 + 1,883,125 rels 24/11 fivemack 105-106A+R: (a) 1,988,962 rel in 2.60Msec K10/2500 + (r) 2,026,728 rel in 2.46Msec C2/2400 24/11 fivemack 106-107A+R: (a) 1,950,983 rel in 2.69Msec various + (r) 2,024,601 rel in 2.45Msec various Last fiddled with by fivemack on 2009-11-24 at 20:39
 2009-09-09, 23:53 #2 fivemack (loop (#_fork))     Feb 2006 Cambridge, England 6,323 Posts Sieving yields measured over a 1k range and extrapolated idealwise Attached Thumbnails
 2009-09-09, 23:54 #3 fivemack (loop (#_fork))     Feb 2006 Cambridge, England 6,323 Posts Memory usage wouldn't it be nice to attach multiple files to the same post? Attached Thumbnails
 2009-09-09, 23:54 #4 fivemack (loop (#_fork))     Feb 2006 Cambridge, England 6,323 Posts How long it takes Looks like about three CPU-days for a 100k range, so this is a factor three or so slower than 2^877-1 was Attached Thumbnails
 2009-09-10, 05:01 #5 Andi47     Oct 2004 Austria 7×353 Posts I assume that this one will run for several months, so there might be enough time to run it over various weekends (even on a system with "only" 2 GB), so I will reserve a chunk which needs least memory (due to necessarily low factorbase bound(s)): reserving 50M - 51M (r+a) I will run it on only one core of a Core 2 Duo (Win XP 32 bit, 1 GB RAM; testing needed ~800MB Ram and 1.6 GB virtual memory) and will run only when I am out of office (weekends and so, with the 2nd core doing a low-memory-job like GIMPS TF'ing), so it might take quite a while. If it turns out that it does too much swapping (i.e. slowly murdering the harddisk), I might stop and unreserve somewhere in the middle. Edit: I will start in ~1 week to 10 days, when my current c153 (2,1766M) finishes sieving (this one was at ~45.1M rels, 39.7M unique, when I did a filtering run on thuesday). Last fiddled with by Andi47 on 2009-09-10 at 05:33
 2009-09-10, 06:57 #6 Andi47     Oct 2004 Austria 7·353 Posts Suggestion: How about rlim=268435455 (2^28-1)? This might be somewhat more memory efficient. fivemack: Yes, quite possibly; try it if you want and report if it saves anything perceptible. Last fiddled with by fivemack on 2009-09-10 at 08:43
 2009-09-10, 08:35 #7 Batalov     "Serge" Mar 2008 Phi(4,2^7658614+1)/2 23·5·229 Posts Damned if I ever passed a good 1% stake in a computation worthy of the name! Count me in for the treacherous ranges 67-69M a+r. _____ I'll stand under the bridge I laid my hands on.
 2009-09-10, 14:18 #8 bsquared     "Ben" Feb 2007 2×3×557 Posts Looks like the university's 36 k8/1400 cpus are not available now, but happily 40 k8/2000 cpus are... so I'll take 51M-61M A+R. - ben.
2009-09-10, 16:04   #9
Andi47

Oct 2004
Austria

7×353 Posts

Quote:
 Originally Posted by Andi47 Suggestion: How about rlim=268435455 (2^28-1)? This might be somewhat more memory efficient. fivemack: Yes, quite possibly; try it if you want and report if it saves anything perceptible.
OK, I will give it some test runs (today or tomorrow) (just for some 2000 Q's to measure the memory useage).
As I said, I will start the "productive" run in approx. 7-10 days, namely when 2,1766M finished sieving.

2009-09-10, 16:05   #10
bdodson

Jun 2005
lehigh.edu

102410 Posts

Quote:
 Originally Posted by bsquared Looks like the university's 36 k8/1400 cpus are not available now, but happily 40 k8/2000 cpus are... - ben.
Slow here too. I'll take 130M-190M-(a+r). I'll start after the last
two of our marvelous seven firsts finish (1642L should factor today,
the c169 gnfs on Friday, 5p346 should finish sieving sometime today,
11p233 will start today, last one is 5m347). -Bruce

 2009-09-10, 17:24 #11 Andi47     Oct 2004 Austria 46478 Posts benchmark sieving with 16e on the a side from Q=50M to 50M+200 on a P4 (win XP, 32 bit) rlim = 300M max. mem = 874 MB virtual mem. = 1.749 MB total yield: 68, q=50000201 (3.13947 sec/rel) rlim=2^28-1: max. mem = 825.7 MB virtual mem = 1.666 MB total yield: 66, q=50000201 (3.13068 sec/rel) (can please someone verify the timing, hence mine was done on a somewhat busy P4?)

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