Hello Miguel, this is caused by the shared memory mempool. Per default this shared memory mapping has a size of 512 MB. You can use the "mpool_sm_size" parameter to reduce size e.g.
mpirun -mca mpool_sm_size <SIZE> ... Thanks, Sven On Friday 25 August 2006 15:04, Miguel Figueiredo Mascarenhas Sousa Filipe wrote: > Hi there, > I'm using openmpi-1.1 on a linux-amd64 machine and also a linux-32bit x86 > chroot environment on that same machine. > (distro is gentoo, compilers: gcc-4.1.1 and gcc-3.4.6) > > In both cases openmpi-1.1 shows a +/-400MB overhead in virtual memory usage > (virtual address space usage) for each MPI process. > > In my case this is quite troublesome because my application in 32bit mode is > counting on using the whole 4GB address space for the problem set size and > associated data. > This means that I have a reduction in the size of the problems which it can > solve. > (my aplication isn't 64bit safe yet, so I need to run in 32bit mode, and use > effectively the 4GB address space) > > > Is there a way to tweak this overhead, by configuring openmpi to use smaller > buffers, or anything else ? > > I do not see this with mpich2. > > Best regards, > > -- > Miguel Sousa Filipe >
