CHAPTER SEVEN PARALLEL PROCESSING © Prepared By: Razif Razali

Contents Multiple Processor Organizations Symmetric Multiprocessors © Prepared By: Razif Razali

Introduction Introduction Traditionally, the computer has been viewed as a sequential machine Most computer programming languages require the programmer to specify algorithms as sequences of instructions Processors executes programs by executing machine instructions in a sequence and one at a time Each instructions is executed in a sequence of operations (fetch instruction, fetch operation, perform operation, store results) A traditional way to increase system performance is to use multiple processors that can execute in parallel to support a given workload. The two most common multiple-processor organizations are Symmetric multiprocessors (SMPs) and clusters More recently, nonuniform memory access (NUMA) have been introduced commercially © Prepared By: Razif Razali

Multiple Processor Organization. Types of Parallel Processor Systems are : Single instruction, single data stream - SISD Single instruction, multiple data stream - SIMD Multiple instruction, single data stream - MISD Multiple instruction, multiple data stream- MIMD © Prepared By: Razif Razali

Single instruction, single data stream - SISD Single processor executes a single instruction stream to operate on data stored in single memory. Uni-processor fall into this category Single instruction, single data stream - SISD © Prepared By: Razif Razali

Single instruction, multiple data stream – SIMD A single machine instruction controls simultaneous execution of a number of processing elements on a lockstep basis. Each processing element has associated data memory, so that each instruction is executed on different set of data by different processors. Example : Vector and array processors Single instruction, multiple data stream - SIMD

MISD & MIMD Multiple instruction, single data stream - MISD Sequence of data Transmitted to set of processors Each processor executes different instruction sequence Never been implemented   Multiple instructions, multiple data stream- MIMD Set of processors Simultaneously execute different instruction sequences Different sets of data SMPs, clusters and NUMA systems MIMD is divided into two : Shared Memory (tightly coupled) : Distributed Memory (loosely coupled) © Prepared By: Razif Razali

Multiple instruction, multiple data stream - MIMD shared memory © Prepared By: Razif Razali

Multiple instruction, multiple data stream- MIMD distributed memory © Prepared By: Razif Razali

Taxonomy of Parallel Processor Architectures © Prepared By: Razif Razali

Symmetric Multiprocessor A stand alone computer with the following characteristics : There are two or more similar processors of comparable capability These processors share the same main memory and I/O facilities and are interconnected by a bus or other internal connection scheme, such that memory access time is approximately the same for each processor All processors share access to I/O devices Either through same channels or different channels that provide paths to same devices All processors can perform the same functions (hence the term symmetric) The system is controlled by an integrated operating system that providing interaction between processors and their programs at the job, task, file and data element levels © Prepared By: Razif Razali

Symmetric Multiprocessor Advantages Performance If some work can be done in parallel, then a system with multiple processors will yield greater performance than one with a single processor of the same type Availability Since all processors can perform the same functions, failure of a single processor does not stop the system Incremental growth User can enhance performance by adding additional processors Scaling Vendors can offer range of products based on number of processors © Prepared By: Razif Razali

Block Diagram of Tightly Coupled Multiprocessor © Prepared By: Razif Razali

Symmetric Multiprocessor CONCLUSIONS Types of Parallel Processor Systems are : Single instruction, single data stream - SISD Single instruction, multiple data stream - SIMD Multiple instruction, single data stream - MISD Multiple instruction, multiple data stream- MIMD Symmetric Multiprocessor © Prepared By: Razif Razali

END OF THESE SUBJECT © Prepared By: Razif Razali