MPICH (and LAM) will cycle through the nodes in order if you specify more than are in the machines file (or running your lamd). -np 5 on two single-cpu machines would give you this cpu0: processes 0 2 4 cpu1: processes 1 3 you can see this if you run 'mpirun -v -np $NP' with LAM's mpirun. Not sure about mpich. this also allows you to run with any -np you want on a single system, though you're computer won't be interactivly usable with -np larger than 2 or 3. -Lucas On Wed, Jan 28, 2004 at 07:16:57PM -0300, Fernan Aguero wrote: > +----[ Lucas Carey <lcarey@odd.bio.sunysb.edu> (28.Jan.2004 11:57): > | > | You should be fine using -np 3 instead of -np2. MPICH will > | start up the third process on the master. Also, try the > | cvs version if you have any troubles, as it contains a lot > | of bugfixes. You can get a nightly tarball from: > | http://mpiblast.sf.net/mpiblast-latest.tar.gz > | -Lucas > | > +----] > > Thanks Lucas, > > that did it! Although I have yet to understand the output of > mpiblast --debug, I can now see CPU activity increase in the > master, coincident with the start of a mpiblast process. > > I'm still confused as to what is happening ... -np 3 with 2 > database segments? But perhaps it's just something like: > process 0 -> master (management) > process 1 -> node (process execution) > process 2 -> master, now acting as a node (process execution) > > Is this documented somewhere? Where have I missed > reading? :) > > Fernan