Nvidia Corporation

Intel Corporation

Aneesh Aggarwal

Ross Segelken

Kevin Koschoreck

Paul Wasson

Tameesh Suri

In one embodiment, a microprocessor is provided. The microprocessor includes instruction memory and a branch prediction unit. The branch prediction unit is configured to use information from the instruction memory to selectively power up the branch prediction unit from a powered-down state when fetched instruction data includes a branch instruction and maintain the branch prediction unit in the powered-down state when the fetched instruction data does not include a branch instruction in order to reduce power consumption of the microprocessor during instruction fetch operations.

Branch prediction power reduction

In one embodiment, a microprocessor is provided. The microprocessor includes a branch prediction unit. The branch prediction unit is configured to track the presence of branches in instruction data that is fetched from an instruction memory after a redirection at a target of a predicted taken branch. The branch prediction unit is selectively powered up from a powered-down state when the fetched instruction data includes a branch instruction and is maintained in the powered-down state when the fetched instruction data does not include an instruction branch in order to reduce power consumption of the microprocessor during instruction fetch operations.

In one embodiment, a method for controlling an instruction cache including a least-recently-used bits array, a tag array, and a data array, includes looking up, in the least-recently-used bits array, least-recently-used bits for each of a plurality of cacheline sets in the instruction cache, determining a most-recently-used way in a designated cacheline set of the plurality of cacheline sets based on the least-recently-used bits for the designated cacheline, looking up, in the tag array, tags for one or more ways in the designated cacheline set, looking up, in the data array, data stored in the most-recently-used way in the designated cacheline set, and if there is a cache hit in the most-recently-used way, retrieving the data stored in the most-recently-used way from the data array.

Instruction cache power reduction

Mechanisms for predicting whether a memory access may be a page hit or a page miss and applying different page policies (e.g., an open page policy or a close page policy) based on the prediction are disclosed. A counter may be used to determine a hit rate (e.g., a percentage or a ratio of the number of memory accesses that are page hits). The processing device may apply different page policies based on the hit rate. A memory access history (that includes data indicating a sequence or list of memory accesses) may be used to identify a counter from a plurality of counters. The processing device may apply different page policies based on the value of the counter (e.g., based on whether the counter is greater than a threshold).

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Portland, OR, United States of America

Aneesh Aggarwal