Coherence protocol tables

Abstract

An agent is provided to include state table storage to hold a set of state tables to represent a plurality of coherence protocol actions, where the set of state tables is to include at least one nested state table. The agent further includes protocol logic associated with the state table storage, the protocol logic to receive a coherence protocol message, and determine a coherence protocol action of the plurality of coherence protocol actions from the set of state tables based at least in part on the coherence protocol message.

1 . An apparatus comprising:
 an agent including:
 state table storage to hold a set of state tables to represent a plurality of coherence protocol actions, wherein the set of state tables is to include at least one nested state table; 
 protocol logic associated with the state table storage, the protocol logic to:
 receive a coherence protocol message; and 
 determine a coherence protocol action of the plurality of coherence protocol actions from the set of state tables based at least in part on the coherence protocol message. 
 
   
     
     
         2 . The apparatus of  claim 1 , wherein the nested state table comprises a particular state table also linked to in at least one other state table in the set of state tables. 
     
     
         3 . The apparatus of  claim 2 , wherein the particular state table corresponds to a sub-action of an action corresponding to the other state table. 
     
     
         4 . The apparatus of  claim 2 , wherein the particular state table is linked to by a plurality of different state tables in the set of state tables. 
     
     
         5 . The apparatus of  claim 1 , wherein the protocol layer logic is to:
 identify a particular state table in the set of state tables corresponding to the message;   identify a row of the particular table corresponding to attributes of the message; and   identifying a reference to the nested state table in the row;   wherein the coherence protocol action is to be determined based at least in part on the nested state table.   
     
     
         6 . The apparatus of  claim 5 , wherein the particular state table includes one or more columns corresponding to current states and one or more columns corresponding to next states, and the reference to the nested state table is included in the columns corresponding to next states. 
     
     
         7 . The apparatus of  claim 6 , wherein the coherence protocol action includes transitioning to another state specified by one or more cells in the columns corresponding to next states. 
     
     
         8 . The apparatus of  claim 1 , wherein the message comprises at least one of a snoop, a data message, a completion, and a forward response message. 
     
     
         9 . The apparatus of  claim 1 , wherein the set of tables embodies a formal specification of a protocol. 
     
     
         10 . The apparatus of  claim 9 , wherein the protocol comprises a coherence protocol. 
     
     
         11 . The apparatus of  claim 9 , wherein the set of tables are machine-parsable tables. 
     
     
         12 . The apparatus of  claim 1 , wherein the set of tables comprises explicitly non-deterministic tables. 
     
     
         13 . The apparatus of  claim 12 , wherein the set of tables lack bias fields. 
     
     
         14 . An apparatus comprising:
 state table storage to hold a set of state tables to represent a plurality of coherence protocol actions, wherein the set of state tables is to include at least one nested state table;   a test engine adapted to validate at least a portion of a state machine of a particular protocol, wherein validation of the state machine comprises simulating coherence protocol actions of an agent and the set of state tables is to be used to simulate the coherence protocol action of the agent in accordance with the particular protocol.   
     
     
         15 . The apparatus of  claim 14 , wherein the particular protocol comprises a coherence protocol. 
     
     
         16 . The apparatus of  claim 14 , wherein the test engine is further to generate a testbench agent from the set of state tables. 
     
     
         17 . The apparatus of  claim 16 , wherein generating a testbench agent comprises generating at least one Murphi model from the set of state tables. 
     
     
         18 . The apparatus of  claim 17 , wherein the generating the testbench agent further comprises translating the Murphi model into at least one class definition. 
     
     
         19 . The apparatus of  claim 16 , wherein the testbench agent, when executed, is to simulate requests and responses of the agent. 
     
     
         20 . The apparatus of  claim 14 , wherein the set of state tables comprise at least one nested state table. 
     
     
         21 . The apparatus of  claim 20 , wherein the nested state table comprises a particular state table linked to in at least one other state table in the set of state tables. 
     
     
         22 . The apparatus of  claim 21 , wherein the nested state table corresponds to a subaction of an action corresponding to the other state table. 
     
     
         23 . A method comprising:
 receiving a coherence protocol message;   identifying a particular state table in the set of state tables corresponding to the message, wherein the set of state tables includes one or more nested state tables;   identifying a reference to another, nested state table in particular state table; and   determining a response to the message based at least in part on contents of the other state table.   
     
     
         24 . The method of  claim 23 , wherein the other table corresponds to a sub-action of an action corresponding to the particular state table, wherein the message corresponds to the action. 
     
     
         25 - 30 . (canceled) 
     
     
         31 . A system comprising:
 a home agent to service requests to a coherent memory space;   a cache agent communicatively coupled to the home agent, the cache agent to make requests of the coherent memory space according to a coherence protocol; and   a set of state tables representing a state machine of the coherence protocol, wherein the set of state tables are to be used by one or both of the home agent and cache agent and the set of state tables includes at least one nested state table.   
     
     
         32 . The system of  claim 31 , wherein the cache agent is further to receive responses to the requests of the coherent memory space from the home agent. 
     
     
         33 . The system of  claim 32 , wherein the cache agent is to determine a response from the set of state tables. 
     
     
         34 . The system of  claim 33 , wherein the response is based at least in part on content of the nested state table. 
     
     
         35 . The system of  claim 31 , wherein the set of state tables are explicitly non-deterministic.