Symmetric vs Asymmetric Multiprocessing

Symmetric vs Asymmetric Multiprocessing

Asymmetric multiprocessing - In asymmetric multiprocessing (ASMP), the operating system typically sets aside one or more processors for its exclusive use. The remainder of the processors run user applications. As a result, the single processor running the operating system can fall behind the processors running user applications. This forces the applications to wait while the operating system catches up, which reduces the overall throughput of the system. In the ASMP model, if the processor that fails is an operating system processor, the whole computer can go down.

Symmetric mMultiprocessing - Symmetric multiprocessing (SMP) technology is used to get higher levels of performance. In symmetric multiprocessing, any processor can run any type of thread. The processors communicate with each other through shared memory.
SMP systems provide better load-balancing and fault tolerance. Because the operating system threads can run on any processor, the chance of hitting a CPU bottleneck is greatly reduced. All processors are allowed to run a mixture of application and operating system code. A processor failure in the SMP model only reduces the computing capacity of the system.

SMP systems are inherently more complex than ASMP systems. A tremendous amount of coordination must take place within the operating system to keep everything synchronized. For this reason, SMP systems are usually designed and written from the ground up.

SIMD(Single-Instruction Stream Multiple-Data Stream)

A graphical representation of a True, Distributed Memory SIMD architecture

                         

 This architecture is essential in the parallel world of computers. Its ability to manipulate large vectors and matrices in minimal time has created a phenomenal demand in such areas as weather data and cancer radiation research.

The architecture consists of a set of identical processing elements (PEs), capable of performing the same operation on different data sets simultaneously. The SIMD allows for a faster and better way to visualize graphics, rendering them almost flawlessly as well as creating them faster.

SIMD architecture is two fold; True SIMD and Pipelined SIMD: 

• True SIMD
  • Distributed Memory
  • Shared Memory
• Pipelined SIMD

                                                  MIMD(Multiple Instruction stream, Multiple Data stream)

•  MIMD has clearly emerges the architecture of choice for general-purpose mutiprocessors.
•  MIMD machines offer flexibility.
•  With the correct hardware and software support, MIMDs can function as single user machines focusing on high performance for one application, as multiprogrammed machines running many tasks simultaneously, or as some combination of these functions.
•  There are two types of MIMD architectures: distributed memory MIMD architecture, and shared memory MIMD architecture.