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DATA-AWARE CACHE STATE MACHINE

  • US 20080172531A1
  • Filed: 03/25/2008
  • Published: 07/17/2008
  • Est. Priority Date: 01/30/2004
  • Status: Active Grant
First Claim
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1. A method for controlling a cache, comprising:

  • managing data in the cache by assigning at least one state to each portion of the cache data, wherein managing each portion of the cache data is enabled by a state machine comprising a plurality of states and a set of state transitions;

    associating each of the plurality of states with a control structure;

    associating each portion of the cache data with a set of attributes; and

    enabling each of the plurality of states to be aware of the cache data, wherein each state includes at least one of;

    a Free state where the cache data contains unvalidated data;

    a Clean state where the cache data is valid and clean and no flush is required;

    a Dirty state where the cache data is valid and dirty and a flush is required;

    a Sticky state where the cache data is valid and clean and was accessed at least twice by at least one of a read operation or a write operation;

    a StickyDirty state where the cache data contains valid dirty data that was accessed at least twice by at least one of a read operation or a write operation;

    a Flush state where the cache data contains valid dirty data that is to be written to a storage device; and

    a Hash state where the cache is in the process of getting valid data from at least one of the physical storage device or a host.

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