|
|
|
|
|
| Berkeley cache |
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| coherence |
||||
| protocol: |
||||
| state transition |
||||
| diagram |
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|
|
|
|
| The
Berkeley |
|||
| protocol is |
|||
| representative
of |
|||
| how
typical bus- |
|||
| based
SMPs work |
|||
|
|
|
|
| Q: What has |
|||
| to
happen on a |
|||
| “Bus
read |
|||
| miss”? |
|||
|
|
|
|
| 1. INVALID |
|||
| 2. VALID: clean,
potentially shared, unowned |
|||
| 3. SHARED-DIRTY:
modified, possibly shared, owned |
|||
| 4. DIRTY: modified,
only copy, owned |
|||
