Hi BeoGuys, I am actually using Linux Debian distribution 2.1 and I have setup a 8 processors beowulf cluster. I am actually using portland compilers. I compiled mpich-1.2.0 and my application VASP (a density funcional software). I know that VASP is working well under other Beo-clusters, but not on mine :-((((( Adding more processors to mpirun -np MORE, I get a BIGGER total elaped time. For istance, with 2 processor, the USER time decreases of 70% (right, as it should do) but the system time explodes of 1 order or magnitude. speed(2 nodes, 2 processor) is almost same of speed(1 node, 1 processor), but with 4 processors, the total speed is 1/3 of the original one. The system time is huge and the cluster is useless. So I supposed to have a problem in my network, since MPI is able to rsh everywhere, lauch jobs, and the mpi-benchmark says 6MBytes/seconds (which size ?). I have read the Linux TCP poor Performance: http://www.icase.edu/coral/LinuxTCP.html I have done this patch. No improvement. I have, 3com 905 10/100 (driver 0.99L) cards with a cabletron 100 switch, debian 2.1, PGI compiler suite, MPICH and LAM compiled with PGI compilers, vasp source (it has been reported going fast in a beo-cluster). Netpipe gives me some reasonable numbers for the bandwitdh. Thanks
Stefano Curtarolo
