| 摘要 |
In response to a need to initiate a global operation, a bus master within a multiprocessor system issues a combined token and operation request on a bus coupled to the bus master. The combined token and operation request solicits a token required to complete the global operation and identifies the global operation to be processed with the token, if granted. Upon receiving a combined response acknowledging both the token and operation portions of the combined request, the bus master treats the global operation as complete. If a combined response acknowledging the token portion of the combined request but retrying the operation portion (i.e., at least one snooper is busy processing a previous global operation), the bus master issues an operation request (only) for the operation portion of the combined request. If the combined response retries both the token and operation portions of the combined request, the bus master issues a token request (only) and, when granted the token, issues an operation request (only) until the global operation is complete. A single token permitting execution of only one global operation is employed, with release implied by either a combined response acknowledging both the token and operation portions of the combined request or an operation request (only).
|
