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Old 2019-06-14, 15:35   #1761
chris2be8's Avatar
Sep 2009

5·389 Posts

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.

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Old 2019-06-14, 16:02   #1762
VBCurtis's Avatar
Feb 2005
Riverside, CA

22·19·59 Posts

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, 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.

./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, 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!
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Old 2019-06-24, 15:04   #1763
cubaq's Avatar
Mar 2016

1110102 Posts
Default poly for C156 kindly request

Would anyone be willing to do poly search on that one C156- 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,

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 different C156
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Old 2019-06-25, 02:59   #1764
swellman's Avatar
Jun 2012

11×263 Posts

cubaq - I will help you with this search but it will be a few days before I can start. Finishing another poly search.
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Old 2019-06-25, 09:26   #1765
cubaq's Avatar
Mar 2016

3A16 Posts
Default OK

Thanks swellman, Ok for me...

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Old 2019-06-25, 13:02   #1766
RichD's Avatar
Sep 2008

2×7×227 Posts
Default C156 Poly

Here is a quick overnight run using msieve-GPU.
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
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Old 2019-06-26, 11:06   #1767
cubaq's Avatar
Mar 2016

2×29 Posts
Default C156 Poly

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

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Old 2019-07-01, 14:11   #1768
richs's Avatar
Aug 2002
Benicia, California

2·11·53 Posts
Default C180 poly


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.

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!

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Old 2019-07-01, 15:35   #1769
RichD's Avatar
Sep 2008

2·7·227 Posts
Default C180 Poly

I'll put a GPU on it starting at 1M.
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Old 2019-07-02, 00:37   #1770
swellman's Avatar
Jun 2012

B4D16 Posts
Default C180 poly

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

Last fiddled with by swellman on 2019-07-02 at 00:38
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Old 2019-07-03, 15:57   #1771
RichD's Avatar
Sep 2008

317810 Posts
Default C180 Poly

Early baseline.
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
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