Dynamically modifying queued transactions in a cache memory system

A method of handling operations in a cache system, comprising:

• in response to a central processing unit issuing a first operation that is unable to complete in a cache memory, storing the first operation in a corresponding entry of a buffer unit and queuing a first transaction in a first entry of a bus transaction queue;
• modifying a first transaction type of said first transaction in response to an event occurring prior to execution of the first transaction, wherein the first transaction type is indicative of whether the transaction requires data;
• in response to the central processing unit issuing a second operation that is unable to complete in the cache memory, storing the second operation in a corresponding entry of the buffer unit and queuing a second transaction in a second entry of the bus transaction queue, wherein the second transaction is of a second transaction type;
• and
• modifying the transaction type of said second transaction from the second transaction type to the first transaction type in response to an event occurring prior to execution of the second transaction, wherein one and only one of said first and second transaction types requires data.

A computer system, comprising;

• a central processing unit including a load/store unit;
• a cache memory coupled to said load/store unit;
• a buffer unit coupled to the cache memory, the buffer unit comprised of a plurality of buffer unit entries suitable for temporarily storing operations generated by the central processing unit that are temporarily unable to complete in the cache memory, each buffer unit entry includes a single-bit transaction type field indicative of whether the corresponding transaction requires data via said system bus;
• a bus transaction queue coupled to the buffer unit, wherein the bus transaction queue includes a plurality of entries wherein each bus transaction queue entry includes a pointer to one of the plurality of buffer unit entries;
• and
• wherein the buffer unit, in response to a first operation initiated by the load/store unit that is unable to complete in the cache memory, is configured to buffer the first operation in a corresponding entry of the buffer unit and queue a first transaction in a first entry of the bus transaction queue, and further wherein said buffer unit is further configured to modify the first transaction from a first transaction type to a second transaction type prior to execution in response to an event occurring after the queuing of the first transaction, wherein the transaction type is indicative of whether the transaction requires data and wherein one and only one of said first and second transaction types requires data.