MSI Invalidate Protocol

• Read obtains block in “shared”

  • even if only cache copy

• Obtain exclusive ownership before writing

  • BusRdx causes others to invalidate (demote)
  • If M in another cache, will flush
  • BusRdx even if hit in S
    • promote to M (upgrade)

• What about replacement?

  • S->I, M->I as before

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