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Old 2018-07-19, 02:13   #571
kriesel
 
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"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest

116318 Posts
Default new behavior: 16 stage 2 residue values taking turns

anomalous Quadro 5000 m350000071 cudapm1 V0.20 20130923 CUDA 5.5 on Windows, interim stage 2 residues:

After a normal looking stage 1, the 120 residues output in stage 2 at NRP=4 are repetitive, over a very limited subset of 16 values,
listed below by ascending value, and that look suspicious by their regularity. (I'm used to runs with pseudorandom looking stage 1 and stage 2 residues. This exponent/gpu combination had seemingly well behaved stage 1 residues but peculiarities throughout stage 2.
Code:
_____8___4___2___1 difference appearing in the respective bit positions
0xfff7fffbfffdfffe
0xfff7fffbfffdffff

0xfff7fffbfffffffe
0xfff7fffbffffffff

0xfff7fffffffdfffe
0xfff7fffffffdffff

0xfff7fffffffffffe
0xfff7ffffffffffff


0xfffffffbfffdfffe
0xfffffffbfffdffff

0xfffffffbfffffffe
0xfffffffbffffffff

0xfffffffffffdfffe
0xfffffffffffdffff

0xfffffffffffffffe
0xffffffffffffffff
End of stage 1 and beginning of stage 2 looked normal. Stage 2 was using 1863MB of 2.5GB on the gpu. At stage 2 wrapup/gcd, it dropped to 746MB.
Code:
Iteration 3650000 M350000071, 0xfa26579b34919a34, n = 20412K, CUDAPm1 v0.20 err = 0.12109 (20:01 real, 48.0195 ms/iter, ETA 22:37)
Iteration 3675000 M350000071, 0x3ca8420d52bd5a27, n = 20412K, CUDAPm1 v0.20 err = 0.11719 (20:01 real, 48.0155 ms/iter, ETA 2:37)
M350000071, 0x509e08b93355b407, n = 20412K, CUDAPm1 v0.20
Stage 1 complete, estimated total time = 49:05:07
Starting stage 1 gcd.
M350000071 Stage 1 found no factor (P-1, B1=2550000, B2=31875000, e=0, n=20412K CUDAPm1 v0.20)
Starting stage 2.
Using b1 = 2550000, b2 = 31875000, d = 2310, e = 2, nrp = 4
Zeros: 1527348, Ones: 1520172, Pairs: 260423
Processing 1 - 4 of 480 relative primes.
Inititalizing pass... done. transforms: 198, err = 0.11328, (4.77 real, 24.0679 ms/tran,  ETA NA)
Transforms: 50660 M350000071, 0xfffffffbfffffffe, n = 20412K, CUDAPm1 v0.20 err = 0.11328 (21:53 real, 25.9248 ms/tran, ETA 43:39:45)

Processing 5 - 8 of 480 relative primes.
Inititalizing pass... done. transforms: 229, err = 0.10547, (5.98 real, 26.1210 ms/tran,  ETA 43:42:27)
Transforms: 50812 M350000071, 0xfff7fffbfffdffff, n = 20412K, CUDAPm1 v0.20 err = 0.10547 (21:57 real, 25.9243 ms/tran, ETA 43:19:29)

Processing 9 - 12 of 480 relative primes.
Inititalizing pass... done. transforms: 231, err = 0.10547, (5.99 real, 25.9324 ms/tran,  ETA 43:20:31)
Transforms: 50810 M350000071, 0xfff7fffffffdffff, n = 20412K, CUDAPm1 v0.20 err = 0.10547 (21:57 real, 25.9239 ms/tran, ETA 42:57:55)

Processing 13 - 16 of 480 relative primes.
Inititalizing pass... done. transforms: 241, err = 0.10547, (6.24 real, 25.8988 ms/tran,  ETA 42:58:31)
Transforms: 50762 M350000071, 0xfff7fffbfffffffe, n = 20412K, CUDAPm1 v0.20 err = 0.10547 (21:56 real, 25.9241 ms/tran, ETA 42:35:58)

Processing 17 - 20 of 480 relative primes.
Inititalizing pass... done. transforms: 247, err = 0.10547, (6.40 real, 25.9017 ms/tran,  ETA 42:36:30)
Transforms: 50814 M350000071, 0xfffffffbfffffffe, n = 20412K, CUDAPm1 v0.20 err = 0.10547 (21:57 real, 25.9239 ms/tran, ETA 42:14:22)
Etc. It concluded with a result line no factor found.
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