From: hjstein@bfr.co.il (Harvey J. Stein) Newsgroups: comp.parallel.mpi,comp.parallel.pvm Subject: Re: Poor MPI performance with collection of Linux workstations Date: 18 Mar 1999 12:46:21 +0300 Organization: Unspecified Organization Message-Id: References: <36ED325A.69D8C9B8@rrsg.ee.uct.ac.za> <7cn7up$4tq$1@grandprime.binc.net> <36F00B68.99E9187@ece.neu.edu> Cc: hjstein@bfr.co.il Xref: ukc comp.parallel.mpi:4776 comp.parallel.pvm:8144 Srinidhi writes: > Harvey J. Stein wrote: > > > > I don't have an answer to your problem, but I have a similar problem. > > > I'm running Linux and have just recently upgraded all machines to the > > > 2.2.3 kernel, hoping my problems would be solved. My problems persist. I > > > have nine machines, one of which is a 4-processor box. > > > > Are they small packets? If so, here's a patch from the linux-kernel > > mailing list that might help: > > I have a similar problem. A 1 Kbyte or larger packet takes less > time (~ 1ms) than a 4 byte mesage (~15ms). This is for PVM on Linux > (Redhat 5.1). Does this patch also fix the problem in PVM? PVM does > not use TCP/IP, AFAIK. AFAIK, the patch only has to do with TCP, not with UDP. I suggest emailing a bug report to the linux-kernel mailing list. Be sure to include the output of a tcpdump showing the problem, or people won't really be able to do anything about it. -- Harvey J. Stein BFM Financial Research hjstein@bfr.co.il