page_title: MOSI protocol
section_title: Operations
hierarchical_section_title: MOSI protocol / Operations
caption_attribution_description: English: A finite state machine showing the processor transactions for the MOSI protocol.
context_page_description: The MOSI protocol is an extension of the basic MSI cache coherency protocol. It adds the Owned state, which indicates that the current processor owns this block, and will service requests from other processors for the block.
context_section_description: In MOSI protocol, each cache has the following requests:
  PrRd - Processor request to read a cache block.
  PrWr - Processor request to write into a cache block.
  BusRd - Snooped request indicating that there is a read request to a cache block made by another processor.
  BusRdX - Snooped request indicating that there is a write request to a cache block made by another processor that does not have the block.
  BusUpgr - Snooped request depicting that there is a write request to a cache block made by another processor that already has the block in its cache.
  Flush - Snooped request after which the cache block is placed on the bus for a cache to cache transfer.
caption: A finite state machine showing the processor transactions for the MOSI protocol.
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