Ensuring orderly forward progress in granting snoop castout requests

A system, comprising:

• a plurality of masters configured to access data, wherein one or more of said plurality of masters has a cache memory associated with it, wherein each of said plurality of cache memories is associated with a snoop controller;
• one or more slaves configured to store data;
• and
• a bus coupling said plurality of masters to said one or more slaves, wherein said bus comprises:
• logic for receiving a plurality of snoopable transfer requests from one or more masters, wherein each of said plurality of snoopable transfer requests comprises a request tag, wherein said request tag identifies a first order of a request issued from a master;
• logic for broadcasting said plurality of snoopable transfer requests in a second order;
• logic for receiving a castout request comprising a first request tag associated with a first snoopable transfer request from a first snoop controller;
• and
• logic for servicing said castout request in said second order of broadcasting said plurality of snoopable transfer requests based on said first request tag.

A system, comprising:

• a plurality of masters configured to access data, wherein one or more of said plurality of masters has a cache memory associated with it, wherein each of said plurality of cache memories is associated with a snoop controller;
• and
• a bus coupling said plurality of masters, wherein said bus comprises:
• logic for receiving a plurality of snoopable transfer requests from one or more masters, wherein each of said plurality of snoopable transfer requests comprises a request tag, wherein said request tag identifies a first order of a request issued from a master;
• logic for broadcasting said plurality of snoopable transfer requests in a second order;
• logic for receiving a castout request comprising a first request tag associated with a first snoopable transfer request from a first snoop controller;
• and
• logic for servicing said castout request in said second order of broadcasting said plurality of snoopable transfer requests based on said first request tag.