Apple Inc.

Steven R Hutsell

James Vash

Harshavardhan Kaushikkar

Gaurav Garg

Per Hakan Hammarlund

Ramesh B Gunna

Farid Nemati

Brian P Lilly

Gregory S Mathews

Lior Zimet

Sergio Kolor

Lital Levy-Rubin

Jonathan M Redshaw

Sagi Lahav

Shawn Munetoshi Fukami

Eran Tamari

Sergio V Tota

Bernard Joseph Semeria

Derek R Kumar

Kevin C Wong

Yi Chun Chen

Kalpana Bansal

Era K Nangia

Steven John Fishwick

Tzach Zemer

A system including a plurality of processor cores, a plurality of graphics processing units, a plurality of peripheral circuits, and a plurality of memory controllers is configured to support scaling of the system using a unified memory architecture.

Scalable system on a chip

A system may include multiple coherent agents, where a given coherent agent includes one or more caches configured to cache data. Memory controller circuitry may control one or more memory circuits from which the one or more caches are configured to cache data and maintain a directory that tracks which of the multiple coherent agent circuits is caching copies of a plurality of cache blocks and states of the cached copies in the multiple coherent agent circuits. A first agent may transmit a first request for a first cache block. The first agent may store, in request buffer circuitry, information corresponding to the first request then detect a second snoop from a second agent circuit to the first cache block. The first agent may absorb the second snoop, including to store information corresponding to the second snoop with the information corresponding to the first request in the request buffer circuitry.

Scalable cache coherency protocol

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

A scalable cache coherency protocol for system including a plurality of coherent agents coupled to one or more memory controllers is described. The memory controller may implement a precise directory for cache blocks from the memory to which the memory controller is coupled. Multiple requests to a cache block may be outstanding, and snoops and completions for requests may include an expected cache state at the receiving agent, as indicated by a directory in the memory controller when the request was processed, to allow the receiving agent to detect race conditions. In an embodiment, the cache states may include a primary shared and a secondary shared state. The primary shared state may apply to a coherent agent that bears responsibility for transmitting a copy of the cache block to a requesting agent. In an embodiment, at least two types of snoops may be supported: snoop forward and snoop back.

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

In an embodiment, a system on a chip (SOC) comprises a semiconductor die on which circuitry is formed, wherein the circuitry comprises a plurality of agents and a plurality of network switches coupled to the plurality of agents. The plurality of network switches are interconnected to form a plurality of physical and logically independent networks. A first network of the plurality of physically and logically independent networks is constructed according to a first topology and a second network of the plurality of physically and logically independent networks is constructed according to a second topology that is different from the first topology. For example, the first topology may a ring topology and the second topology may be a mesh topology. In an embodiment, coherency may be enforced on the first network and the second network may be a relaxed order network.

Multiple independent on-chip interconnect

Growing community of inventors

San Jose, CA, United States of America

Steven R Hutsell