Marvell International Limited

Arm Limited

Tom Marko Hameenanttila

Sujat Jamil

R Frank O'Bleness

Joseph Anthony Delgross

David E Miner

Jeffrey Kehl

Kim Richard Schuttenberg

Richard F Bryant

Frank O'Bleness

Russell J Robideau

Adi Habusha

Hong-Yi Chen

Franco Ricci

Timothy S Beatty

Robert Wiesner

Varun Palivela

Rong Zhang

An apparatus comprises a branch predictor to predict an outcome of a branch instruction to be processed by processing circuitry, based on branch prediction state information stored in one or more branch prediction structures, and a call path tracking element to store call path tracking information, where in response to a procedure calling instruction processed by the processing circuitry, the call path tracking information is updated depending on at least a portion of an address associated with the procedure calling instruction. The one or more branch prediction structures include at least one call-path-indexed branch prediction structure which is indexed based on an index value which depends on a portion of the call path tracking information stored in the call path tracking element.

Branch prediction structure indexed based on return address popped from a call-return stack

A method can include executing a store instruction that instructs storing of data at an address and, in response to the store instruction, inserting a preloading instruction after the store instruction but before a dependent load instruction to the address. Executing the store instruction can include invalidating a data entry of a cache array at an address of the cache array corresponding to the address and writing the data to a backing memory at an address of the backing memory corresponding to the address. The preloading instruction can cause filling the data entry of the cache array, at the address of the cache array corresponding to the address, with the data from the backing memory at the address of the backing memory corresponding to the address and validating the data entry of the cache array.

Method and apparatus for use of a preload instruction to improve efficiency of cache

The present disclosure provides a device comprising a memory translation buffer configured to manage (i) a first request for a first search in a page table, wherein the first request is responsive to a first null result of a search for a first address translation in a translation look-aside buffer ('TLB') and (ii) a second request for a second search in the page table, wherein the second request is responsive to a second null result of a search for a second address translation in the TLB. The memory translation buffer is also configured to compare a virtual memory address of the first request to a virtual memory address of the second request and, based on a result of the comparing the virtual memory address of the first request to the virtual memory address of the second request, access the page table to perform the second search.

Method and apparatus for optimizing translation of a virtual memory address into a physical memory address in a processor having virtual memory

A microprocessor includes a front end module and a schedule queue module. The front end module is configured to retrieve first instructions, corresponding to a first thread, from an instruction cache, and retrieve second instructions, corresponding to a second thread, from the instruction cache. The front end module is also configured to decode the first instructions into first decoded instructions, and decode the second instructions into second decoded instructions. The schedule queue module is configured to selectively store the first decoded instructions and the second decoded instructions from the front end module and, for each stored decoded instruction, selectively issue the stored decoded instruction to an execution module. The schedule queue is further configured to reject storing an additional one of the first decoded instructions from the front end module in response to a count of the stored first decoded instructions in the schedule queue module exceeding a threshold.

Method and apparatus for sharing instruction scheduling resources among a plurality of execution threads in a multi-threaded processor architecture

Apparatus having corresponding methods and computer-readable media comprise: a speculative store buffer memory; and a speculative store buffer controller comprising a store address comparator to compare an address of a received store instruction with addresses of store instructions allocated in the speculative store buffer memory, and a store age comparator to compare an age of the received store instruction with an age of a matching store instruction allocated in the speculative store buffer memory, wherein the speculative store buffer controller replaces the store instruction allocated in the speculative store buffer memory with the received store instruction responsive to the store instruction allocated in the speculative store buffer memory being younger than the received store instruction.

Method and apparatus for processing speculative, out-of-order memory access instructions

A cache management unit manages allocation and configuration of a cache memory that is utilized by a multi-threaded processor. In some implementations, the cache management unit is configured to determine a number of active threads being executed by the multi-threaded processor, assign a separate cache unit to each active thread when the number of active threads is equal to a maximum number of active threads supported by the multi-threaded processor, and assign more than one cache unit to an active thread when the number of active threads is less than the maximum number of active threads.

Thread-aware cache memory management

Systems, methods, and other embodiments associated with echo cancellation are described. According to one embodiment, an apparatus includes a plurality of first registers configured to respectively store information related to a performance of a processor and a second register in communication with each of the plurality of first registers. The apparatus also includes logic configured to detect a trigger event; and in response to having detected the trigger event, copy the information related to the performance of the processor respectively in the plurality of first registers into the second register.

Hardware support for performance analysis

A system and method of tracking multiple non-identification tagged requests in a system with multiple responders are disclosed. In one embodiment, an electronic memory system comprises a memory configured to implement a plurality of response queues, wherein one response queue is associated with one responder from a plurality of responders, and wherein a responder is a device capable of resolving the memory request. A tracking module is configured to assign identification information to a memory request that is received and store the identification information in one or more queues of the plurality of response queues; and to transmit the memory request to each responder that is associated with the one or more queues. A response module is configured to associate the identification information in the one or more queues with a response upon receiving the response from the one or more responders.

Method and apparatus for associating requests and responses with identification information

An apparatus including a snoop filter decoupled from a cache and an associated method for snoop filtering are disclosed. The snoop filter is decoupled from the cache such that the cache changes states of lines in the cache from a first state that is a clean state, such as an exclusive (E) state, to a second state that is not a clean state, such as a modified (M) state, without the snoop filter's knowledge. The snoop filter buffers addresses of replaced lines that are unknown to be clean until a write-back associated with the replacement lines occurs, or until actual states of the replaced lines are determined by the snoop filter generating a snoop. A multi-level cache system in which a reallocation or replacement policy is biased to favor replacing certain lines such as inclusive lines, non-temporal lines or prefetched lines that have not been accessed, is also disclosed.

Method and apparatus having a snoop filter decoupled from an associated cache and a buffer for replacement line addresses

A processor for processing loop instructions can include an instruction reorder structure and a loop processing controller. The instruction reorder structure is configured to store decoded instructions according to program order and issue the decoded instructions for execution out of program order. The loop processing controller is configured to detect a loop in the decoded instructions stored in the instruction reorder structure and cause the instruction reorder structure to reissue the decoded instructions that form the loop for re-execution.

Detecting and reissuing of loop instructions in reorder structure

Devices, systems, methods, and other embodiments associated with a cache memory are described. In one embodiment, a cache tag array includes tag banks. The cache memory further includes a bank selector configured to receive an address and to apply a hash function that maps the address to one of the tag banks.

Cache memory bank selection

Aspects of the disclosure provide methods for cache efficiency. A method for cache efficiency can include storing data in a buffer entry in association with a cache array in response to a first store instruction that hits the cache array before the first store instruction is committed. Further, when a dependent load instruction is subsequent to the first store instruction, the method can include providing the data from the buffer entry in response to the first dependent load instruction. When a second store instruction overlaps an address of the first store instruction, the method can include coalescing data of the second store instruction in the buffer entry before the second store instruction is committed. When the second store instruction is followed by a second dependent load instruction, the method can include providing the coalesced data from the buffer entry in response to the second dependent load instruction.

Method and apparatus for improving cache efficiency

A processor that executes instructions out of program order is described. In some implementations, a processor detects whether a second memory operation is dependent on a first memory operation prior to memory address calculation. If the processor detects that the second memory operation is not dependent on the first memory operation, the processor is configured to allow the second memory operation to be scheduled. If the processor detects that the second memory operation is dependent on the first memory operation, the processor is configured to prevent the second memory operation from being scheduled until the first memory operation has been scheduled to reduce the likelihood of having to reexecute the second memory operation.

Speculative scheduling of memory instructions in out-of-order processor based on addressing mode comparison

According to some embodiments, an apparatus having corresponding methods includes a storage module configured to store data and instructions; a first processor pipeline configured to process the data and instructions when the first processor pipeline is selected; a second processor pipeline configured to process the data and instructions when the second processor pipeline is selected; and a selection module configured to select either the first processor pipeline or the second processor pipeline.

Dynamic pipeline reconfiguration including changing a number of stages

A programmable cache and cache access protocol that can be dynamically optimized with respect to either power consumption or performance based on a monitored performance of the cache. A monitoring unit monitors cache misses, load use penalty, and/or other performance parameter, and compares the monitored values against a set of one or more predetermined thresholds. Based on the comparison results, a cache controller configures the programmable cache to operate in a parallel mode, to increase cache performance at the cost of greater power consumption, or in a serial mode, to conserve power at the cost of unnecessary performance. A banked cache memory that supports aligned and unaligned instruction fetches using a banked access strategy, and a cache access controller that includes a prefetch capability are also described.

Growing community of inventors

Phoenix, AZ, United States of America

Tom Marko Hameenanttila