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-   -   Polynomial Request Thread (https://www.mersenneforum.org/showthread.php?t=18368)

chris2be8 2019-06-14 15:35

Hello SethTro,

What sort of GPU do you have?
What operating system do you use?

msieve polynomial selection needs a Nvidia GPU and a suitable level of Nvidia drivers and CUDA toolkit (old cards may only work with old drivers and CUDA toolkit).

Start by carefully reading Readme.nfs shipped with msieve, especially the section on Polynomial Selection Using Graphics Cards.

Chris

VBCurtis 2019-06-14 16:02

You won't get to verify their results, because msieve does quite a bit of randomizing of search spaces. When you run the msieve-gpu first stage (-np1), you'll see messages go by for each initial-coefficient like "searching piece 4 of 9". The search space grows as the input size grows, so up at C190 it may search 1 of 40 pieces for each leading coefficient.
I've managed to break all my linux-CUDA installs by way of not disallowing ubuntu to update the drivers, so I can't find you polys. Sorry!
A quick primer on msieve poly searching:
small leading coeffs produce higher skews, and there are sieving disadvantages to really high skew, so we often start a search at a higher coeff value than we would in CADO. For a C150, I'd start at 10k or so. If your GPU is modern, I'd add -t 2 before the quotes; if GPU still isn't running 90% or more, increase threads to 3 or 4. I use a 750ti, and -t 2 isn't necessary for me.

./msieve -np1 -nps "10000,500000" -s polyfile1

Let it run just a few seconds into the firehose of screen output, and kill it. Delete polyfile1.ms, as those hits aren't useful to us.
Open msieve.log, note the stage1 and stage2 norms selected by msieve. Divide stage1 by 8 or 10, divide stage2 by 30, and invoke the command line with those values included:

./msieve -np1 -nps "stage1_norm=3e25 stage2norm=3e26 10000,500000" -s polyfile1

Restricting stage 1 norm alters the number of raw polys sent from the GPU to the CPU for size-optimizing. If msieve is using 75% or more of a CPU thread, I'd tighten (lower) stage1 norm to reduce the flood of raw polys going to the CPU; the buffer is not large, so some of the flood is getting discarded when the CPU reaches 100%. Deciding what to divide the default norms by is a matter of taste, and the "best" values may vary by GPU model vs CPU speed. I've been mostly running C190+ searches this year, and size-opt up there takes meaningful CPU time so it pays to restrict stage1norm, but at C150 the CPU may never get busy so you may not need to restrict it at all.

Restricting stage2 norm alters the number of size-optimized polys written to the poly file. You'll do root-optimizing separately, but that takes a long time per poly so it's of no use to write thousands of polys to disk. At C150, a GPU-day is more than sufficient for a search, and I'd want to root-opt no more than 200 polys. So, if you find 10 or 20 polys per hour in polyfile1 you'll have plenty. Most folks use text-handling commands to sort and truncate the file to their top-nnn candidates for root-opting; on big projects I often root-opt 100 polys per day, which takes an hour or two on a single core.

root-opt:
./msieve -npr min_evalue={something about halfway between the default e-value in msieve.log and the lower "expected poly score" in the log} -s polyfile1

This will read size-opted polys from polyfile1.ms, root-optimize them, and write any results scoring better than your command-line e-value to polyfile1.p. The best-scoring poly will be written to msieve.log. You may wish to leave min_evalue at default your first couple runs, to make sure you get output; msieve actually sets a rather high default minimum in the C150 range so you won't get a flood of polys like you would at C130 or C180.

Good luck!

cubaq 2019-06-24 15:04

poly for C156 kindly request
 
Would anyone be willing to do poly search on that one [FONT=Calibri][URL="http://factordb.com/index.php?id=1100000000635616163"][COLOR=#0000ff]C156[/COLOR][/URL][/FONT]- possibly good as e = 2.5e-12 ?
With simple yafu (no CADO nor Msieve) I receive poly not better than e = 1.952e-012.

Thanks a lot in advance,
cubaq

PS. Please use format of nfs.dat.p I.E.

n: 203842833410712927553257265361853710692524121905134240210466716917926957911239954497820098762494002374151535725052813818242975458769575385036774198081803881
# norm 4.670468e-15 alpha -7.289913 e 2.517e-12 rroots 3
skew: 2971710.70
c0: -23274189821224357309898280156200576505
c1: 10988311336612933471289325784498
c2: -5481397393317645261159383
c3: -12931688786744927070
c4: 3722948949516
c5: 581400
Y0: -810893988138705201024296657396
Y1: 4900160628720071

PSS. Above one was create some time ago by VBCurtis (Thanks once more) for [U]different[/U] C156

swellman 2019-06-25 02:59

cubaq - I will help you with this search but it will be a few days before I can start. Finishing another poly search.

cubaq 2019-06-25 09:26

OK
 
Thanks swellman, Ok for me...


cubaq

RichD 2019-06-25 13:02

C156 Poly
 
Here is a quick overnight run using msieve-GPU.
[CODE]n: 650759922121463236833360513774841181001461339483871226353038981828162693800832313686778309941432412192442518331823116725305359878570887450020904465995102343
# expecting poly E from 2.25e-12 to > 2.59e-12
Y0: -1256357577423906213823822875695
Y1: 9412240894197941
c0: 108692363424111326378001853721796664128
c1: 152856550024062825326683903429032
c2: 286127630701918219650254
c3: -12040494181681137622
c4: -514554716877
c5: 207900
skew: 4974186.55
# size 3.791e-15, alpha -7.263, combined = 2.503e-12 rroots = 3[/CODE]

cubaq 2019-06-26 11:06

C156 Poly
 
Thank You RichD, thank You swellman - the poly seems to be good enough.


cubaq

richs 2019-07-01 14:11

C180 poly
 
Greetings,

Any help that folks can provide in finding a poly for the C180 of of Aliquot sequence 829332 i3682 would be greatly appreciated. The composite has been ecm'ed to t60.

[CODE]556940527200132132854208867567328661523961665167691935298836583617867683327352415435587145291214586514910588208005629756713211655009152862726284530753453151223562309591761233828943[/CODE]

I am running a CPU poly search on this number for coefficients up to 1,001 using msieve through YAFU, and my intention is to use NFS@Home for sieving once a suitable poly is found.

Thanks very much!

Rich

RichD 2019-07-01 15:35

C180 Poly
 
I'll put a GPU on it starting at 1M.

swellman 2019-07-02 00:37

C180 poly
 
I’ll search 1 < c5 < 1M with msieve-GPU.

RichD 2019-07-03 15:57

C180 Poly
 
Early baseline.
[CODE]N: 556940527200132132854208867567328661523961665167691935298836583617867683327352415435587145291214586514910588208005629756713211655009152862726284530753453151223562309591761233828943
# expecting poly E from 7.95e-14 to > 9.14e-14
R0: -51339310176802195647918234796070211
R1: 307307686784268491
A0: 10500314747871565996625552457853698964170320
A1: 225275976148768244904479980725708308
A2: -267724887937708298946752397360
A3: 4718334196608579062471
A4: 587015698064354
A5: 1561560
skew 23443607.85, size 1.309e-17, alpha -7.506, combined = 8.302e-14 rroots = 5[/CODE]


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