Multiprocessor Operating System refers to the use of two or more central processing
units (CPU) within a single computer system. These multiple CPUs are in a close
communication sharing the computer bus, memory and other peripheral devices.
Multiprocessor systems are also called as parallel systems or tightly coupled systems.
These types of systems are used when very high speed is required to process a large
volume of data. These systems are generally used in environment like satellite control,
weather forecasting etc.
Advantages:
Increased Throughput: By increasing the number of processors, we expect to get more
work done in less time.
Economy of scale: Multiprocessor systems can cost less than equivalent multiple single-
processor systems, because they can share peripherals, mass storage, and power
supplies.
Increased reliability: As there are multiple processors in the system, failure of one
processor will not halt the system, only slow it down. This ability to continue providing
services proportional to the level of surviving hardware is called as graceful
degradation.
Disadvantages:
Multiprocessing can cause a system to change its memory access model from uniform
memory access (UMA) to non-uniform memory access (NUMA). NUMA is a kind of
situation in which some parts of memory may take longer to access than other parts
creating a performance penalty.
Types of multiprocessor systems:
There are two types: multiprocessor systems using asymmetric multiprocessing (ASMP)
and multiprocessor systems using symmetric multiprocessing (SMP).
In ASMP each processor is assigned a specific task. There is one master processor which
controls the system and the other processors are the slave processors. The master
processor allocates and schedules the work to the slave processors. Slave processors
perform the task given to them by master processor.
In SMP no master-slave relationship exists between processors. Each processor has its
own set of registers as well as local cache. All the processors share the same physical
memory and all of them run an identical copy of operating system
units (CPU) within a single computer system. These multiple CPUs are in a close
communication sharing the computer bus, memory and other peripheral devices.
Multiprocessor systems are also called as parallel systems or tightly coupled systems.
These types of systems are used when very high speed is required to process a large
volume of data. These systems are generally used in environment like satellite control,
weather forecasting etc.
Advantages:
Increased Throughput: By increasing the number of processors, we expect to get more
work done in less time.
Economy of scale: Multiprocessor systems can cost less than equivalent multiple single-
processor systems, because they can share peripherals, mass storage, and power
supplies.
Increased reliability: As there are multiple processors in the system, failure of one
processor will not halt the system, only slow it down. This ability to continue providing
services proportional to the level of surviving hardware is called as graceful
degradation.
Disadvantages:
Multiprocessing can cause a system to change its memory access model from uniform
memory access (UMA) to non-uniform memory access (NUMA). NUMA is a kind of
situation in which some parts of memory may take longer to access than other parts
creating a performance penalty.
Types of multiprocessor systems:
There are two types: multiprocessor systems using asymmetric multiprocessing (ASMP)
and multiprocessor systems using symmetric multiprocessing (SMP).
In ASMP each processor is assigned a specific task. There is one master processor which
controls the system and the other processors are the slave processors. The master
processor allocates and schedules the work to the slave processors. Slave processors
perform the task given to them by master processor.
In SMP no master-slave relationship exists between processors. Each processor has its
own set of registers as well as local cache. All the processors share the same physical
memory and all of them run an identical copy of operating system
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