MPI parallel programming example tutorial part1.mpi parallel environment and encoding model

1. parallel programming mode-message transmission:

Message Passing libraries with common functions include picl, PVM, parmacs, P4, and MPI. The message passing libraries customized for specific systems include MPL, NX, and cmmd.

The main disadvantage of the Message Passing model is that explicit DATA division and process synchronization are required during the programming process. Therefore, you need to spend a lot of energy to solve data dependencies and prevent deadlocks.

2. Basic concepts of MPI message communication

• Cache area

The MPI Environment defines three cache zones:

Application Buffer Zone	It refers to the address space for saving the data to be sent or received, which is the content part defined in the message format.
System Buffer Zone	The MPI Environment is the storage space for communication.
Buffer Zone registered by the user to the System	When you use some APIs (mpi_bsend ),ProgramAnd then register it to the MPI Environment for communication.

• Communicator)

Communication Sub-nodes are the basic infrastructure for managing processes and communications in the MPI Environment. (Eg: mpi_comm_world ). Operations on a process must be placed in the communication sub-body.

• Communication Protocol:

The MPI Environment adopts the following communication protocols:

Communication Protocol (EAGER)	It is always assumed that the target process is capable of saving message data. Note: This method reduces synchronization latency and simplifies programming, but requires a considerable number of buffers.
Centralized communication protocol (rendezvous)	The send action can be executed only after the target is ready. Note: This method ensures reliability and security, and provides the possibility of eliminating multiple data records, but increases programming complexity (with wait/test mechanisms ), it also brings about synchronization latency (it takes time to wait for the process to permit ).
Message disconnection protocol (short)	The message data is sent together with the envelope.

From: MPI parallel programming example tutorial

Zhang wusheng waited for Tsinghua University Press

More: http://blog.donews.com/me1105/archive/2011/02/10/115.aspx