Discussion related to cado-nfs

[Bernardo Boncompagni <bernardo.boncompagni@gmail.com>]

Hi all,

within the scope of the aliquot sequence project at mersenneforum.org I have been running several factorizations in the past few weeks with CADO-NFS and everything went smoothly until I encountered a bug preventing a factorization to complete. I first encountered it on a C114 and then on the C107 54022122323205311359700529131254845253584832080092810873601245077747279904751944559089001546838958178759103 = 6892192422790360694669529583587636497846216763819494386433 * 7838162228984026472885414974266767581580262988991

So i ran some tests on two machines with the following specifications:

- "EC2": an Amazon EC2 instance with 3.3 GHz AMD EPYC processors, 4 cores, 8 threads, 16 GiB RAM, Ubuntu 18.04 fully updated
- "WSL": a Windows 10 PC with Intel Core i7-7800X processors, 6 cores, 12 threads, 32 GiB RAM, WSL Ubuntu 18.04 fully updated

All versions of CADO-NFS were installed with git clone https://gitlab.inria.fr/cado-nfs/cado-nfs.git.

All tests were run with the default command line cado-nfs.py <N> workdir=<workdir> unless specified.
When they failed, all tests did with the same "corrupted table" error, see attached log (c105.log.zip).
When failed, the error seems reproducible with the same command line on the same machine.

Test results follow.

Failed on EC2, CADO-NFS with timestamp July 22 (two runs).
Failed on EC2, CADO-NFS with timestamp August 18.
Failed on EC2, CADO-NFS with timestamp August 18, parameters -t 6.
Passed on WSL, CADO-NFS with timestamp March 17.
Failed on WSL, CADO-NFS with timestamp August 18.
Failed on WSL, CADO-NFS with timestamp August 18, parameters -t 8.

So it looks like whatever it is, it does not depend on the processor type, on the number of cores and on the actual cores used, and was introduced some time between March 17 and July 22.

I also attach the requested make cmake output (cmake.log.zip) and gcc -v (gcc.log.zip) for the WSL machine. Let me know if you also need those of EC2.

Thank you for your time.

Attachment: c105.log.zip
Description: Zip archive

Attachment: cmake.log.zip
Description: Zip compressed data

Attachment: gcc.log.zip
Description: Zip compressed data