Mechanism for handling I/O transactions with known transaction length to coherent memory in a cache coherent multi-node architecture

An apparatus comprising:

• an incoming request buffer to store requests relating to read and write operations, the requests including addresses to be read or written;
• an outgoing request buffer coupled to the incoming request buffer;
• bus logic to interface with a bus, the bus logic coupled to the incoming request buffer and the outgoing request buffer;
• control logic to interface with and coupled to the incoming request buffer, the outgoing request buffer, and the bus logic, the control logic to identify a request to read a current copy of a data line, the control logic to respond to the request to read a current copy by finding a data line within a cache-coherent multi-node system, receive a copy of the data line without disturbing a state associated with the data line, provide the copy of the data line to a requestor originating the request, and determine whether the data line is a last data line of a transaction associated with the request based on a known transaction length of the transaction.

A system comprising:

• a first processor;
• a second processor;
• an I/O subsystem;
• a scalability port coupled through a bus to the first processor and coupled through the bus to the second processor, the scalability port further coupled through the bus to the I/O subsystem, the scalability port including:
• an incoming request buffer to store requests relating to read and write operations, the requests including addresses to be read or written;
• an outgoing request buffer coupled to the incoming request buffer;
• bus logic to interface with the bus, the bus logic coupled to the incoming request buffer and the outgoing request buffer;
• and
• control logic to interface with and coupled to the incoming request buffer, the outgoing request buffer, and the bus logic, the control logic to identify a request to read a current copy of a data line, the control logic to respond to the request to read a current copy by finding a data line within a cache-coherent multi-node system, receive a copy of the data line without disturbing a state associated with the data line, provide the copy of the data line to a requestor originating the request, and determine whether the data line is a last data line of a transaction associated with the request based on a known transaction length of the transaction.

A system comprising:

• a first processor;
• a second processor;
• an I/O subsystem;
• a scalability port coupled through a first bus to the first processor and coupled through the first bus to the second processor, the scalability port further coupled through a second bus to the I/O subsystem, the scalability port including:
• an incoming request buffer to store requests relating to read and write operations, the requests including addresses to be read or written;
• an outgoing request buffer coupled to the incoming request buffer;
• bus logic to interface with the first bus and the second bus, the bus logic coupled to the incoming request buffer and the outgoing request buffer;
• and
• control logic to interface with and coupled to the incoming request buffer, the outgoing request buffer, and the bus logic, the control logic to identify a request to read a current copy of a data line, the control logic to respond to the request to read a current copy by finding a data line within a cache-coherent multi-node system, receive a copy of the data line without disturbing a state associated with the data line, provide the copy of the data line to a requestor originating the request, and determine whether the data line is a last data line of a transaction associated with the request based on a known transaction length of the transaction.

A method comprising:

• requesting a current copy of a data line;
• receiving a current copy of the data line;
• processing the data line independently of a surrounding system;
• and
• determining whether the data line is a last data line of a transaction based on a known transaction length of the transaction.

An apparatus comprising:

• means for receiving a request for a current copy of a data line;
• means for finding the data line within a cache-coherent multi-node system;
• means for copying the data line without disturbing a state associated with the data line coupled to the means for receiving;
• means for providing a copy of the data line in response to the request coupled to the means for finding the data line;
• and
• means for determining whether the data line is a last data line of a transaction based on a known transaction length of the transaction.