Apple Inc.

Lucent Technologies Inc.

Alcatel-lucent USA Inc.

Alcatel Lucent

Acatel-lucent USA Inc.

Gregory S Mathews

Shane J Keil

Lakshmi Narasimha Murthy Nukala

Sukalpa Biswas

Thejasvi Magudilu Vijayaraj

Kai Lun Hsiung

Yanzhe Liu

Farid Nemati

Rakesh L Notani

Philip Arnold Ferolito

Eric T Anderson

Steven R Hutsell

Mike Morrison

Peter Fu

Thejasvi Magudilu Vijavaraj

Harshavardhan Kaushikkar

Bernard Joseph Semeria

James Vash

Derek R Kumar

Kevin C Wong

Yi Chun Chen

Kalpana Bansal

Jeonghee Shin

Sanjay Jain

Era K Nangia

Sukulpa Biswas

Manu Gulati

Robert E Jeter

Rohit Kumar Gupta

Tao Zhang

Avinash Gyanendra Mani

Rohit Natarajan

Fabien S Faure

Venkata Ramana Malladi

James Bauman

Liang Deng

Jorge Alejandro Aguilar

Kai Lun Hsuing

Lakshmi Narasimha Nukala

Enming Zheng

Techniques are disclosed relating to memory controllers and rate-limited traffic. In some embodiments, an apparatus includes memory controller circuitry configured to satisfy different quality-of-service parameters for multiple different classes of request traffic. The apparatus may also include multiple agents configured to send requests to the memory controller circuitry, where the agents operate according to a rate limit for a first class of traffic. The apparatus may include cache circuitry. In some embodiments, based on an allocation in the cache circuitry for a read operation of the first class that causes an eviction from the cache circuitry, the control circuitry is configured to perform a write operation of evicted data: as the first class of traffic and without counting the write operation toward the rate limit for the first class of traffic. In contrast, the control circuitry may count other write operations of the first class of traffic toward the rate limit.

Handling eviction write operations caused by rate-limited traffic

A memory control circuit coupled to multiple memory ranks may receive read and write requests for a different ranks of the multiple memory ranks. The memory control may allocate write requests to different slots based on the write requests target memory rank, and may adjust the number of slots available for a given memory rank during a write turn to improve write efficiency. The memory control circuit may also determine a number of ranks switches within a read turn based on whether a particular quality-of-service requirement associated with the read requests is being satisfied.

Write arbiter circuit with per-rank allocation override mode

Techniques for scheduling memory operations are disclosed in which alternate read/write commands within a multi-bank memory operation are delayed beyond a minimum timing parameter in order to increase memory data bus utilization. The remaining read/write commands are not delayed beyond the minimum timing parameter. Every other clock cycle (e.g., even clock cycles) within the memory operation is reserved for activate commands, while other commands such as sync and read/write are scheduled on the intervening clock cycles (e.g., odd clock cycles). For memory devices for which a sync command (which causes a clock of the memory data bus to start) is to precede a corresponding read/write command by a number of clock cycles that would place it in a cycle reserved for activate commands, a particular operation mode is disclosed in which the memory device internally delays a received sync command.

Memory device bandwidth optimization

Techniques are disclosed relating to memory error tracking and logging. In some embodiments, a memory cache controller circuitry is configured to track, using multiple circuit entries, numbers of detected correctable errors associated with multiple respective locations, and in response to detecting a threshold number of correctable errors for a particular location, generate a signal to the one or more processors that identifies the particular location. In some embodiments, the memory cache controller circuitry includes multiple circuit entries for tracking uncorrectable errors.

Memory error tracking and logging

Techniques are disclosed relating to improving memory reliability. In some embodiments, memory circuitry includes memory cells configured to store data, interface circuitry, and on-die error correcting code (ECC) circuitry. The ECC circuitry may check read data from the memory cells for errors and correct detected correctable errors to generate corrected data. The memory circuitry may provide read data to a requesting circuit via the interface circuitry, including one or more sets of corrected data from the on-die ECC circuitry. The memory circuitry may provide a decoding status flag (DSF) via the interface circuitry, including to: set the DSF to a first value in response to no error being detected for a given set of provided read data, set the DSF to a second value in response to a correctable error that was detected and corrected by the on-die ECC circuitry to provide a given set of read data, and set the DSF to a third value in response to an uncorrectable error detected by the on-die ECC circuitry.

Decoding status flag techniques for memory circuits

Read arbiter circuit with dual memory rank support

Systems, apparatuses, and methods for addressing bank hotspotting are described. A computing system includes a memory controller with an arbiter for determining how to arbitrate access to one or more memory device(s) for received requests. The arbiter categorizes each request in a manner that helps to ensure fair virtual channel distribution across the banks of the memory device(s). The category system includes bank hotspotting functions to give banks that have more requests more chances to go over banks with fewer requests. The category system is implemented proportionally with more category credits given to banks with higher bank depths within the virtual channel.

Memory bank hotspotting

Techniques are disclosed relating to bandwidth compensation for certain memory traffic at high temperatures. In some embodiments, processor circuitry is configured to execute memory access operations for multiple traffic classes, including a first traffic class (e.g., real-time traffic) associated with a bandwidth quality-of-service parameter and a second traffic class (e.g., low-latency traffic). In some embodiments, memory controller circuitry is configured to access storage circuitry to perform the memory access operations, determine a temperature value associated with the storage circuitry, and, based on detection of a first temperature scenario for the storage circuitry, allocate memory access operations among the first and second traffic class according to a first allocation policy. In some embodiments, in response to detection of a second temperature scenario for the storage circuitry, memory controller circuitry allocates memory access operations among both traffic classes according to a second allocation policy. The second allocation policy may provide greater bandwidth for the first class than the first allocation policy.

Temperature-based bandwidth compensation for memory traffic

Techniques are disclosed relating to multi-activation techniques for wire operations with multiple partial writes. In some embodiments, a memory controller is configured to access data in a memory device that supports partial writes having a first size using read-modify-write operations and non-partial writes having a second size that is greater than the first size. In some embodiments, the memory controller is configured to queue a first write operation having the second size, where the first write operation includes multiple partial writes. In some embodiments, the memory controller is configured to send separate activate signals to the memory device to activate a bank of the memory device to perform different proper subsets of the multiple partial writes. This may allow interleaving of other accesses to a memory bank and merging of writes while waiting for a current activation, in some embodiments.

Multi-activation techniques for partial write operations

Techniques are disclosed relating to improving memory reliability, e.g., in the context of memory circuits with limited reliability features. In some embodiments, memory controller circuitry is configured to communicate with memory circuitry via an interface that supports link error detection. The memory controller circuitry may, based on a corruption indicator, transmit a data and parity combination for the first data block that causes the memory circuitry to detect an uncorrectable write interface error. Subsequent reads of the location may therefore cause an uncorrectable error indication. This may advantageously allow the memory controller circuitry to propagate a corruption indicator as an uncorrectable error in the memory circuit, without requiring additional tracking of the indicator by the memory circuit or memory controller, in some embodiments.

Data corruption tracking for memory reliability

Techniques are disclosed relating to merging virtual communication channels in a portion of a computing system. In some embodiments, a communication fabric routes first and second classes of traffic with different quality-of-service parameters, using a first virtual channel for the first class and a second virtual channel for the second class. In some embodiments, a memory controller communicates, via the fabric, using a merged virtual channel configured to handle traffic from both the first virtual channel and the second virtual channel. In some embodiments, the system limits the rate at which an agent is allowed to transmit requests of the second class of traffic, but requests by the agent for the first class of traffic are not rate limited. Disclosed techniques may improve independence of virtual channels, relative to sharing the same channel in an entire system, without unduly increasing complexity.

Communication channels with both shared and independent resources

An apparatus includes a memory circuit and a memory controller circuit. The memory controller circuit may include a write request queue. The memory controller circuit may be configured to receive a memory request to access the memory circuit and determine if the memory request includes a read request or a write request. A received read request may be scheduled for execution, while a received write request may be stored in the write request queue. The memory controller circuit may reorder scheduled memory requests based on achieving a specified memory access efficiency and based on a number of write requests stored in the write request queue.

Ordering memory requests based on access efficiency

Techniques relating to arbitration in a memory controller are disclosed. In some embodiments, the memory controller is configured to transition between read turns and writes turn according to a turn schedule. In some embodiments, the memory controller also receives reports from circuitry requesting memory transactions and determines a current latency tolerance value based on the reports. In some embodiments, the memory controller is configured to switch from a write turn to a read turn prior to a scheduled switch based on the current latency tolerance meeting a threshold value.

Write/read turn techniques based on latency tolerance

Growing community of inventors

Saratoga, CA, United States of America

Gregory S Mathews