Help with LAM
alazur at plogic.com
Thu Jul 13 10:27:25 PDT 2000
Peter Jay Salzman (p at belial.ucdavis.edu) said:
> i found the homepage for LAM and noticed they have RPM's (yay!). we have a
> choice of:
> i'm sure we don't want the src rpm since we're happy with simply using
> supplied binaries.
> what are the differences between the tcp, sysv and usysv rpm's? which one
> should we use? i just started playing around with the cluster, so i'm a
> newbie. any help would be appreciated.
[ Quoted from http://www.mpi.nd.edu/lam/faq/category8.php3#question2 ]
2. What does tcp, sysv, and usysv mean?
LAM provides three client-to-client transport layers which implement the
request progression interface (RPI). The three client-to-client transports are:
tcp The tcp transport uses TCP sockets for all interprocess communication.
usysv The usysv transport is multi-protocol. Processes on the same node
communicate via SYSV shared memory and processes on different nodes
communicate via TCP sockets. It uses spin-locks for shared memory
synchronization as well as a SYSV semaphore or pthread mutex for
synchronizing access to a per node global shared memory pool. The
spin-locks require that the architecture has strongly ordered writes
and this transport is only supported on such platforms. It should be
relatively easy to modify this transport to work on systems with weakly
ordered writes by adding memory barriers in appropriate places.
sysv The sysv transport is the same as the usysv transport except that SYSV
semaphores are used for message synchronization rather than spin-locks.
On some uniprocessor systems (e.g. Linux) the blocking nature of
semaphores can lead to better performance than when using spin-locks.
The usysv transport should give the best performance on SMPs.
[ End quoted material ]
[ Adam Lazur <alazur at plogic.com> ]
[ Paralogic Inc. - www.plogic.com - www.xtreme-machines.com ]
More information about the Beowulf