If you can avoid them it is better to avoid them. However it is always
better to use a MPI_Alltoall than coding your own all to all with
point to point, and in some algorithms you *need* to make a all to all
communication. What you should understand by "avoid all to all" is not
avoid MPI_al
I have always been told that calls like MPI_Barrior() MPI_Allreduce()
and MPI_Alltoall() should be avoided.
I understand MPI_Alltoall() as it goes n*(n-1) sends and thus grows
very very quickly. MPI_Barrior() is very latency sensitive and
generally is not needed in most cases I have seen
Hi again,
Thanks Pak for the link and suggesting to start an "orted" deamon, by doing so
my clients and servers jobs were able to establish an intercommunicator
between them.
However I modified my programs to perform an MPI_Allgather() of a single "int"
over the new intercommunicator to test
Jeff Pummill wrote:
Haha, yeah we found out about that one when trying to run Linpack with
threaded BLAS implementations.
BTW Goto BLAS threaded implementation doesn't use any MPI calls. So you
may build Linpack with Goto_thread + OMPI non-threaded and it will run
without any problem.
Pasha.
Ok, I will do.
Jeff Squyres wrote:
Sure, that would be fine.
Can you write it up in a little more FAQ-ish style? I can add it to
the web page. See this wiki item:
https://svn.open-mpi.org/trac/ompi/wiki/OMPIFAQEntries
On Mar 12, 2008, at 5:33 AM, Pavel Shamis (Pasha) wrote:
Run op
Sure, that would be fine.
Can you write it up in a little more FAQ-ish style? I can add it to
the web page. See this wiki item:
https://svn.open-mpi.org/trac/ompi/wiki/OMPIFAQEntries
On Mar 12, 2008, at 5:33 AM, Pavel Shamis (Pasha) wrote:
Run opensm with follow parameters:
opensm
MPI_THREAD_MULTIPLE is unlikely to work at all (regardless of network)
in the v1.2 series.
On Mar 11, 2008, at 7:31 PM, Brian Budge wrote:
One small (or to some, not so small) note is that full multi-
threading with OpenMPI is very unlikely to work with infiniband
right now.
Brian
On M
Run opensm with follow parameters:
opensm -c -o
It will make 1 loop and will exit (-o parameter). The -c option says to
opensm to generate option file.
The file will be generated under /var/cache/opensm//opensm.opts
Open the file and find line with "subnet_prefix". Replace the prefix
with new
