[CSE]  Advanced Operating Systems 
 COMP9242 2002/S2 
UNSW

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Next: Single-Address-Space Operating Systems Up: 12-mungi Previous: Protection in a SASOS

Subsections

Single Address Space Advantages

Application View

  • Simple naming mechanism - 64 bit address - supported by ``conventional'' hardware.
  • User data structures can contain embedded references to other data.
  • Eliminates excessive copying of data and software pointer translation.

SASOS Advantages: System View

  • Simplifies data migration
  • Simplifies process migration
  • Orthogonality of translation and protection
  • No need for file system -- all disk I/O is paging
  • RAM is cache for VM -- unified buffer & disk cache management
  • Easy to implement zero-copy operations
  • In-place execution -- no need for position-independent code
==> Simplified system implementation and increased performance

SASOS Advantages: Hardware View

  • Virtual caches are no problem
    virtual address maps uniquely to physical address
  • Hardware separating translation from protection could increase performance due to increased TLB coverage
    (e.g. IA-64 protection keys)



Gernot Heiser 2002-10-24