Multiprocessor systems

Objective n the multiprocessors’ organization and implementation n the shared-memory in multiprocessor n static and dynamic connection networks

Structure of Multiprocessor systems n consists of N processors plus interconnections for passing data and control information among the computers. n Up to N different instruction streams can be active concurrently. n The challenge is to put the N processors to work on different parts of a computation,

Structure of MIMD

The fastest supercomputer n located in the Alberta National Laboratory in United States. n This computer is equivalent to 9000 Pentium processors n can handle 21,000x10^8 instructions per second.

Terminology n PE-to-PE u Each processor has its own memory and uses a common bus for intercommunication.

CRAY T3D n Number of Processors u 128 Processor Elements (PEs) n Performance per PE u 150 MFlops / PE n Main Memory u 8 GB Memory (64 MB each PE) n Harddisk u 80 GB temporary disk space n Swap area u 35 GB permanent user disk space

PE-to-PE SIMD machine configuration n Same as an array computer. n The local memory is attached to its own processor with an interconnection network for exchanging data. n The number of arithmetic processors is equal to the number of memory storages.

PE to PE SIMD

Processor-to-memory with N processors and N memories n The Processor-to-memory parallel machine with N processors and N memories n Same as an array computer without a control unit. n The local memory is separated from its own processor and they are linked up by an interconnection network.

PE to Memory

Difference between Multi-processors n MSIMD u It is called multiple-SIMD which can be reconfigured into a number of smaller independent SIMD machines n Partitionable SIMD/MIMD u be partitioned into smaller independent machines of different sizes working in SIMD or MIMD

Simple Uni-processor

Memory access n Access to memory may be blocked temporarily due to the conflicts in the network or the accessed memory module.

Three methods to solve memory access n Buffer network elements u To queue a request in the buffer when a conflict occurs. n Deletion u The processors will delete all but one of the conflicting requests n Either of the about schemes reduces CPU performance.

Multiprocessor interconnection networks n A basic parallel processing system consists of various processors to be linked up by an interconnection network to form interprocess communication.

Example of static network topologies n The processors are predefined with connection paths. n Classified as one-dimensional such as Linear Array, two- dimensional such as Ring, Star, Tree, etc.

Static network (fixed)

Two-way switching box n A dynamic network allows processors to re-route the path (That is why it is called dynamic). n The single-stage network is also called a recirculating network.

Switching box

4x4 switching network (Blocking)

Non-Blocking Network n A non-blocking networking has its ability to connect any input to output n Example is a cross-bar.

Cross bar

Summary n introduced multiprocessors with N processors and M (or N) memory storages. n Interconnected by a network which can be dynamic or static. n Dynamic network can be classified as a blocking or non-blocking network. n Blocking network can be implemented through switching boxes while non-blocking network can be implemented by a cross-bar network.