OS-Distributed Computing

Parallel processing techniques are used to push computing power to its limits. These techniques are frequently employed in the class of machines called supercomputers.

Multiprocessing is the use of multiple processors to execute separate portions of a computation truly simultaneously. The small size of microprocessors makes it reasonable to consider packaging many of them in a single system.

The goal of supercomputers is to push the state of the art in computing to its practical limits. A commercial computer with vector instructions and pipelined floating-point arithmetic operations is referred to as a supercomputer. Supercomputers are very powerful, high-performance machines used mostly for scientific computations. To speed up the operation, the components are packed tightly together to minimize the distance that the electronic signals have to travel. Supercomputers also use special techniques  for removing the heat from circuits to prevent them from burning up because of their close proximity.

A supercomputer is a computer system best known for its high computation speed, fast and large memory systems, and the extensive use of parallel processing. It is equipped with multiple functional units and each unit has its own pipeline configuration. Supercomputers are limited in their use of a number of scientific applications such as numerical weather forecasting, seismic wave analysis and space research.

A measure used to evaluate computers in their ability to perform a given number of floating-point operations per second is referred to as flops. The term megaflops are used to denote million flops and gigaflops to denote billion flops.

The first supercomputer developed in 1976 is the Cray-I supercomputer. It uses vector processing with 12 distinct functional units in parallel. Each functional unit is segments to process the incoming data through a pipeline.

All the functional units can operate concurrently with operands stored in the large number of registers in the CPU.

Cray research extended its supercomputer to a multiprocessor configuration called CRAY X-MP which appeared first in 1982. the CRAY X-MP has two or four identical processors that share I/O and memory. Main memory uses 64-bit words, an indication of the machines design to favor high precision scientific computation. The memory is 32-way interleaved. The CPUs communicate through clusters of shared registers.

The Cedar system was developed at the center for supercomputing research and development at the university of Illinois. It connects eight Alliant FX/8 superminicomputers with a multistage network to 64 global memory modules. The Cosmic cube is a “hypercube” multiprocessor, developed at the California institute of technology. IBM is working on a machine dubbed the TF-1, a supercomputer with a goal of executing 3 trillion double-precision floating point operation per second. This is about 1000 times faster than today’s most powerful supercomputers.
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