Thanks all for the answers,
I am parallelizing tomography algorithm which takes about 5 hours using
single processor.
I want to gain full performance and should reduce the computational
time as short as possible.
I was wondering the SSh/RSH launcher could be a performance issue?(I
am just guessing)
What kind of software/middleware I should use to solve the
network/communication overhead.
(different launchers ,may be Sun Grid Engine,XGrid ? ) I am runing
Debian/Lenny and since the project is academic I want to use OSS ..
Best Regards,
Umanga
Jeff Squyres wrote:
On Jun 29, 2009, at 2:19 AM, vipin kumar wrote:
Q. Since I am using TCP/Ethernet I guess that MPI uses SSH/RSH to
communicate between peers.
Ans. May be you are right. I don't know exactly how peers communicate
in MPI environment, but I can say for sure that OpenMPI uses rsh/ssh
as one of the available launchers.
Open MPI uses two different mechanisms for launching individual MPI
processes vs. MPI communications. rsh/ssh is one of the options that
Open MPI can use for launching MPI processes, but we don't keep those
channels open and don't use them for MPI communications. Individual,
new TCP sockets are opened for MPI_SEND / MPI_RECV (etc.) traffic.
These sockets are not encrypted (like ssh connections would be).
Q. And for that, each peer should have the copy of the application
right?
Ans. Absolutely correct. But If you don't want to copy binaries
manually you should use "--preload-binary" option. OpenMPI will copy
the executables in remote nodes before launching processes, and will
delete when job gets done.
It is almost always good to use latest version. "--preload-binary"
option may be absent in old versions.
It is new in the 1.3 series; it did not exist in the 1.2 series.
