Discuss how processes and resource are bound together? How does process migration take place in heterogeneous environment?

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written 8.7 years ago by

teamques10 ★ 68k

In distributed systems a number of resources are interconnected by a network. The set of resources available to the user can only be used by having some process executing them for the user.
A resource manager schedules the process in a distributed system to make use of the system resource such that resource usage, response time and overhead are optimized. This is how processes and resources are bond together.
In homogenous environment, for process migration the interpretation of data is consistent on the source and destination nodes. No data translation is needed.
But in heterogeneous environment data needs to be translated from the source CPU format to the destination CPU format before it can be executed.
If a system consists of two CPU types then each processor should be able to convert foreign data into its own understandable format. If a third CPU is added then there is another overhead of converting the data format.
Hence a heterogeneous system that consists of n CPU types should have n(n-1) pieces of translation software so that the translation can be done for all nodes.
The figure below explains the overhead due to translation of data during process migration. Processor 1 has to convert three times if it sends to any of the other process and converts to its own format another three times.

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To reduce software complexity external data representation mechanism can be used.
In this mechanism a standard representation is used for transport of data and each process needs to be converted to and from the standard form.
In diagram below the process of converting from a particular format machine representation to an external data representation format which is called serializing and reverse is known as deserializing. Here the sending processor converts only one time.

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The standard data representation format is called external data representation which should have representations for characters, integers and floating point numbers.
Data representation is difficult for floating-point numbers which is done by handling the exponent ant the mantissa
Issues during the design of external data representation are signed-infinity and signed-zero representation.

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