The main purpose of daemon-based communication is development, but depending on the application's decomposition granularity and communication requirement, it may also be entirely adequate for production execution. MPI communication can bypass the LAM daemon for peak performance. The other implementation of the MPI library's low-level communication intends to use the highest performance underlying mechanism, certainly bypassing the LAM daemon and connecting directly between application processes. The availability of optimal C2C implementations will continue to change as architectures come and go. Moreover, interpretation of the MPI guarantee on message progress may confuse the debugging of an application that actually died on envelope overflow.
LAM advertises and guarantees a minimum level of internal resources for message delivery.
It is a promise from the implementation to the application that a minimum amount of envelope buffering will be available to each process pair. Secondly, it ensures that the producer of messages that overflows this resource will be throttled or cited with an error as necessary. A minimum GER is configured when LAM is built. Process Spawning A group of MPI processes can collectively create a group of new processes. An intercommunicator is established for communication.