CST(15)-Multiprocessing Superservers:

Superservers are fully loaded machines; they include multiprocessors, high-speed disk arrays and fault-tolerant features. With the proper division of labor, multiprocessors should improve job throughput and server application speeds. A multiprocessor server is upwardly scalable. Multiprocessing comes in two flavors - Asymmetric and fully Symmetric.

Asymmetric multiprocessing imposes hierarchy and a division of labor among processors. Only one designated processor, the master can run the operating system at any one time. The master controls the slave processors dedicated to specific functions such as disk I/O or network I/O. A coprocessor is an extreme form of codependency; one processor completely controls a slave processor through interlocked special purpose instructions. It has a unique special purpose hardware that is not identical to the main processor.

Symmetric Multiprocessing (SMP) treats all processors as equals. Any processor can do the work of any other processor. Applications are divided into threads that can run concurrently on any available processor. Any processor in the pool can run the operating system kernel and execute user-written threads. SMP improves the performance of the application itself as well as the total throughput of the server system. Ideally the operating system should support SMP by providing three basic functions – a reentrant OS kernel, a global scheduler that assigns threads to available processors and shared I/O structures. SMP requires multiprocessor hardware with some form of shared memory and local instruction caches.
CST(15)-Multiprocessing Superservers: Reviewed by 1000sourcecodes on 21:46 Rating: 5
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