Abstract: A data processor includes a staging buffer, a command queue, a picker, and an arbiter. The staging buffer receives and stores first memory access requests. The command queue stores second memory access requests, each indicating one of a plurality of ranks of a memory system. The picker picks among the first memory access requests in the staging buffer and provides selected ones of the first memory access requests to the command queue. The arbiter selects among the second memory access requests from the command queue based on at least a preference for accesses to a current rank of the memory system. The picker picks accesses to the current rank among the first memory access requests of the staging buffer and provides the selected ones of the first memory access requests to the command queue.

Abstract: A memory controller includes a command queue having an input for receiving memory access commands for a memory channel, and a number of entries for holding a predetermined number of memory access commands, and an arbiter that selects memory commands from the command queue for dispatch to one of a persistent memory and a DRAM memory coupled to the memory channel. The arbiter includes a first-tier sub-arbiter circuit coupled to the command queue for selecting candidate commands from among DRAM commands and persistent memory commands, and a second-tier sub-arbiter circuit coupled to the first-tier sub-arbiter circuit for receiving the candidate commands and selecting at least one command from among the candidate commands.

Abstract: A memory controller includes a command queue that receives and stores decoded memory commands and information related thereto including information indicating a type, a priority, an age, and a region of a memory system for a corresponding decoded memory command, and an arbiter coupled to the command queue and picks selected decoded memory commands among the decoded memory commands from the command queue for dispatch to the memory system by comparing the priority and the age for decoded memory commands having a first type. The arbiter detects when the command queue receives a decoded memory command of a second type opposite to said first type that accesses a first memory region of the memory system, and in response elevates at least one of the priority and the age of a decoded command of the first type that accesses the first memory region already stored in the command queue.

Abstract: A memory controller includes a command queue that receives and stores decoded memory commands and information related thereto including information indicating a type, a priority, an age, and a region of a memory system for a corresponding decoded memory command, and an arbiter coupled to the command queue and picks selected decoded memory commands among the decoded memory commands from the command queue for dispatch to the memory system by comparing the priority and the age for decoded memory commands having a first type. The arbiter detects when the command queue receives a decoded memory command of a second type opposite to said first type that accesses a first memory region of the memory system, and in response performs at least one pre-work action that reduces a latency of the decoded memory command of the second type.

Abstract: A memory controller includes a command queue and an arbiter for selecting entries from the command queue for transmission to a DRAM. The arbiter transacts streaks of consecutive read commands and streaks of consecutive write commands. The arbiter transacts a streak for at least a minimum burst length based on a number of commands of a designated type available to be selected by the arbiter. Following the minimum burst length, the arbiter decides to start a new streak of commands of a different type based on a first set of one or more conditions indicating intra-burst efficiency.

Abstract: A memory controller includes a command queue and an arbiter for selecting entries from the command queue for transmission to a DRAM. The arbiter transacts streaks of consecutive read commands and streaks of consecutive write commands. The arbiter has a current mode indicating the type of commands currently being transacted, and a cross mode indicating the other type. The arbiter is operable to monitor commands in the command queue for the current mode and the cross mode, and in response to designated conditions, send at least one cross-mode command to the memory interface queue while continuing to operate in the current mode. In response to an end streak condition, the arbiter swaps the current mode and the cross mode, and transacts the cross-mode command.

Abstract: A memory controller an arbiter which causes streaks of read commands and streaks of write commands over the memory channel. During a streak, the arbiter monitors an indicator of data bus efficiency of the memory channel. Responsive to the indicator showing that data bus efficiency is less than a designated threshold, the arbiter stops the current streak and start a streak of the other type.

Abstract: A processor transfers prefetch requests from their targeted cache to another cache in a memory hierarchy based on a fullness of a miss address buffer (MAB) or based on confidence levels of the prefetch requests. Each cache in the memory hierarchy is assigned a number of slots at the MAB. In response to determining the fullness of the slots assigned to a cache is above a threshold when a prefetch request to the cache is received, the processor transfers the prefetch request to the next lower level cache in the memory hierarchy. In response, the data targeted by the access request is prefetched to the next lower level cache in the memory hierarchy, and is therefore available for subsequent provision to the cache. In addition, the processor can transfer a prefetch request to lower level caches based on a confidence level of a prefetch request.

Abstract: A processor transfers prefetch requests from their targeted cache to another cache in a memory hierarchy based on a fullness of a miss address buffer (MAB) or based on confidence levels of the prefetch requests. Each cache in the memory hierarchy is assigned a number of slots at the MAB. In response to determining the fullness of the slots assigned to a cache is above a threshold when a prefetch request to the cache is received, the processor transfers the prefetch request to the next lower level cache in the memory hierarchy. In response, the data targeted by the access request is prefetched to the next lower level cache in the memory hierarchy, and is therefore available for subsequent provision to the cache. In addition, the processor can transfer a prefetch request to lower level caches based on a confidence level of a prefetch request.