Symmetric Multiprocessing (SMP)

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Symmetric Multiprocessing (SMP)
REVIEW
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Categories of Computer Systems

• Single Instruction Single Data (SISD)
• single processor executes a single instruction
  stream to operate on data stored in a single
  memory
• Single Instruction Multiple Data (SIMD)
• one instruction is executed on a different set of
  data by the different processors

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Categories of Computer Systems

• Multiple Instruction Single Data (MISD)
• a sequence of data is transmitted to a set of
  processors, each of which executes a different
  instruction sequence. Never implemented
• Multiple Instruction Multiple Data (MIMD)
• a set of processors simultaneously execute
  different instruction sequences on different data
  sets

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Parallel Processor Architecture
MIMD
Distributed memory (self-contained computers)
Shared memory multiprocessor
Clusters
Symmetric multiprocessors (SMP)
Master/Slave
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Symmetric Multiprocessing

• Kernel can execute on any processor
• Typically each processor does self-scheduling
  from the pool of available process or threads
• portions of the kernel can execute in parallel in
  different processors

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Symmetric Multiprocessor Organization
Processor
Processor
Processor
.
.
.
Cache
Cache
Cache
Main Memory
I/O Subsystem
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Multiprocessor OS requirements

• Must provide functionality of a multiprogramming
  OS plus additional features to support multiple
  processors
• Simultaneous concurrent processes or threads
  kernel routines need to be reentrant
• Scheduling done by any processor, can create
  conflicts.
• Synchronization through locks is required.
• Memory management needs to be coordinated in the
  different processors
• Much more complex than just multiprogramming OS.