2013-04-13, 07:12 | #1 |
Jul 2012
D_{16} Posts |
msieve MPI error
Hello ,
I am trying for first time the MPI support in msieve. For my first run, I am using only 1x1 grid. I get this error. What does it mean? Thank you Code:
Msieve v. 1.52 (SVN 880) Fri Apr 12 23:59:41 2013 random seeds: 70f21d5e ef3ba596 MPI process 0 of 1 factoring 37120944689800609412002515056317303932773604020034145686079164382030167043089316373333849352676912740718719896128949056002154056277661151343 (140 digits) no P-1/P+1/ECM available, skipping commencing number field sieve (140-digit input) R0: -32534952778982469485491103546896674762721 R1: 1 A0: -2377 A1: 0 A2: 0 A3: 0 A4: 0 A5: 1 skew 4.73, size 5.749e-14, alpha -0.564, combined = 1.380e-11 rroots = 1 commencing linear algebra initialized process (0,0) of 1 x 1 grid read 406172 cycles cycles contain 2208513 unique relations read 2208513 relations using 20 quadratic characters above 536847050 building initial matrix error: overflow merging ideals Last fiddled with by Batalov on 2013-04-13 at 16:28 Reason: wrapped in /code/ tags |
2013-04-13, 12:46 | #2 |
Tribal Bullet
Oct 2004
3^{2}·5·79 Posts |
It means that a column in the matrix has too many nonzeros in it for the fixed-size buffers the matrix building code uses (1000 in this case)
Note that a matrix of size 2.2M is quite large for a C140, especially for SNFS, so it's likely that you only barely have enough relations to create a matrix. If you sieve a little bit more, the problematic matrix columns will be thrown away and the matrix will build successfully. PS: I see that the original number you were factoring was 203 digits, and that the matrix is actually 400k in size, which is actually remarkably small. The underlying cause is the same (barely enough sieving), but it's unusual to have seen it work. Could you post the filtering log? (as an attachment if it's more than 10k in size) Last fiddled with by jasonp on 2013-04-13 at 13:01 |
2013-04-13, 16:11 | #3 |
Jul 2012
13 Posts |
I tried the -nc1 step again on this machine. Even stranger results.
Code:
Msieve v. 1.52 (SVN 880) Sat Apr 13 05:36:59 2013 random seeds: 982d5ff4 0a09ba06 MPI process 0 of 1 factoring 37120944689800609412002515056317303932773604020034145686079164382030167043089316373333849352676912740718719896128949056002154056277661151343 (140 digits) no P-1/P+1/ECM available, skipping commencing number field sieve (140-digit input) R0: -32534952778982469485491103546896674762721 R1: 1 A0: -2377 A1: 0 A2: 0 A3: 0 A4: 0 A5: 1 skew 4.73, size 5.749e-14, alpha -0.564, combined = 1.380e-11 rroots = 1 commencing relation filtering estimated available RAM is 32177.6 MB commencing duplicate removal, pass 1 read 10M relations read 20M relations read 30M relations read 40M relations read 50M relations read 60M relations found 7010116 hash collisions in 61617384 relations commencing duplicate removal, pass 2 found 4779477 duplicates and 56837907 unique relations memory use: 213.2 MB reading ideals above 720000 commencing singleton removal, initial pass memory use: 1378.0 MB reading all ideals from disk memory use: 1948.4 MB keeping 47348982 ideals with weight <= 200, target excess is 304146 commencing in-memory singleton removal begin with 56837907 relations and 47348982 unique ideals reduce to 39855511 relations and 28825503 ideals in 11 passes max relations containing the same ideal: 163 removing 6751492 relations and 4751492 ideals in 2000000 cliques commencing in-memory singleton removal begin with 33104019 relations and 28825503 unique ideals reduce to 32204736 relations and 23117721 ideals in 8 passes max relations containing the same ideal: 144 removing 5571076 relations and 3571076 ideals in 2000000 cliques commencing in-memory singleton removal begin with 26633660 relations and 23117721 unique ideals reduce to 26023682 relations and 18899805 ideals in 7 passes max relations containing the same ideal: 129 removing 5241972 relations and 3241972 ideals in 2000000 cliques commencing in-memory singleton removal begin with 20781710 relations and 18899805 unique ideals reduce to 20218656 relations and 15056591 ideals in 8 passes max relations containing the same ideal: 108 removing 5059845 relations and 3059845 ideals in 2000000 cliques commencing in-memory singleton removal begin with 15158811 relations and 15056591 unique ideals reduce to 14566468 relations and 11356184 ideals in 7 passes max relations containing the same ideal: 83 removing 4916867 relations and 2916867 ideals in 2000000 cliques commencing in-memory singleton removal begin with 9649601 relations and 11356184 unique ideals reduce to 8959286 relations and 7674883 ideals in 8 passes max relations containing the same ideal: 59 removing 2467642 relations and 1536049 ideals in 931593 cliques commencing in-memory singleton removal begin with 6491644 relations and 7674883 unique ideals reduce to 6047516 relations and 5651320 ideals in 8 passes max relations containing the same ideal: 47 removing 214732 relations and 171346 ideals in 43386 cliques commencing in-memory singleton removal begin with 5832784 relations and 5651320 unique ideals reduce to 5825483 relations and 5472613 ideals in 6 passes max relations containing the same ideal: 47 relations with 0 large ideals: 6543 relations with 1 large ideals: 7546 relations with 2 large ideals: 93140 relations with 3 large ideals: 457709 relations with 4 large ideals: 1142888 relations with 5 large ideals: 1624338 relations with 6 large ideals: 1449097 relations with 7+ large ideals: 1044222 commencing 2-way merge reduce to 3973954 relation sets and 3621084 unique ideals commencing full merge Illegal instruction |
2013-04-13, 16:27 | #4 |
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
89·113 Posts |
Your binary may be compiled for a different processor, if you are getting "Illegal instruction" exit.
Did you build it yourself? Did you modify the Makefile to match the CPU? (in the line OPT_FLAGS = -O3 -fomit-frame-pointer -march=core2 ...) |
2013-04-13, 21:30 | #5 |
Jul 2012
13 Posts |
Thanks Batalov, that helps for -nc1 ! Recompiled with -march=opteron and fixed it.
To be clear, for MPI, does one use different M,N in each command line, e.g. "-nc2 1,4" "-nc2 2,4" etc. for a 4x4 grid? Or should you pass "-nc2 4,4" to each?? Thanks again! |
2013-04-14, 00:07 | #6 |
Tribal Bullet
Oct 2004
3^{2}·5·79 Posts |
Usually your MPI has an 'mpirun' script that you pass a single command line to, with one choice of 'M,N'. That gets used by everybody (if I understand what you're asking)
The best M,N depends on the machine(s), the interconnect(s) between machines, and the size of the problem. Smaller problems will only speed up if you break them up into a few MPI processes. You can also use threads and MPI together; the split between how many threads and how much MPI depends on how good your machine is and how bad your MPI library is. All this is a roundabout way of saying you will need to do some trial and error. |
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