[Cado-nfs-discuss] Block-Wiedemann with MPI

Schmid Johannes schmidjo at inf.ethz.ch
Tue Oct 4 11:05:37 CEST 2011


I'm trying to use cado-nfs-1.0 with MPI enabled, but I have a basic question: is the working directory (wdir) supposed to be accessible/shared for all nodes? For all other steps and for mpi=0 this isn't the case, but with mpi=1 the bwc commands are accessing directories (projectname.bwc) and *.bin files from the working directory. I tried sharing the working directory between the machines, but this caused the computation to slow down significantly. Could this be due to insufficient network speed?

On a different note, I've had problems restarting the factoring after the linear algebra stage aborted due to the problems mentioned above. The symptom is an error message
Error:parameter mpi from <wdir>/<project>.param clashes with value defined earlier from other config files (0 vs. 2) at <bindir>/cadofct.pm line 281.
I think the problem is that before <project>.param is read, the parameters have already been established (either from the default values or by parsing the other param files) and line 281 disallows certain parameters to be redefined. I get by by removing the <project>.param file, but I think that this may be a bug.

Thanks in advance for any help on these issues!

Johannes Schmid

More information about the Cado-nfs-discuss mailing list