Data cache miss lookaside buffer and method thereof
AssigneeInternational Business Machines Corporation
InventorMikko Herman Lipasti
Life of this patent
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Abstract
A data processing system, circuit arrangement, integrated circuit device, program product, and method implement value prediction in a data cache miss lookaside buffer that maintains predicted values only for load instructions that miss a data cache. As a result, whenever a load instruction misses a cache, the predicted value therefor may be retrieved from the buffer concurrently with servicing of the cache miss so that subsequent instructions can be speculatively executed while the actual value is retrieved. By limiting the buffer to storing only predicted values for load instructions that miss the data cache, the size of the buffer can be reduced compared to conventional designs, thereby providing more effective value prediction for a given size of buffer.
Claims25
A circuit arrangement, comprising:
- (a) an execution circuit configured to process a load instruction by initiating retrieval of a value requested by the load instruction from a memory having a cache;
- (b) a buffer storing a predicted value for the load instruction;
- and
- (c) a control circuit, coupled to the execution circuit and the buffer, the control circuit configured to provide the predicted value to the execution circuit when retrieval of the value requested by the load instruction misses the cache;
- wherein the value requested by the load instruction is representative of data to be returned as a result of the load instruction.
A method of executing instructions in a computer, the method comprising:
- (a) determining whether a value requested by a load instruction being executed is stored in a cache;
- and
- (b) in response to determining that the value is not stored in the cache, predicting the value requested by the load instruction;
- wherein the value requested by the load instruction is representative of data to be returned as a result of the load instruction.
A method of executing instructions in a computer, the method comprising:
- (a) storing a value requested by a load instruction in a buffer in response to a cache miss for the value, wherein the value represents a predicted value for a subsequent execution of the load instruction;
- and
- (b) retrieving the value from the buffer during a subsequent execution of the load instruction;
- wherein the value requested by the load instruction is representative of data to be returned as a result of the load instruction.
Dependencies are inferred from the claim text.