Arm Limited

Jamshed Jalal

Phanindra Kumar Mannava

Tushar P Ringe

Mark David Werkheiser

Bruce James Mathewson

Klas Magnus Bruce

Gurunath Ramagiri

Michael Filippo

Ashok Kumar Tummala

Paul Gilbert Meyer

Ramamoorthy Guru Prasadh

Mukesh Patel

Dimitrios Kaseridis

Anitha Kona

Andrew David Tune

Alex James Waugh

Joseph Michael Pusdesris

Sean James Salisbury

Brett Stanley Feero

Daniel Adam Sara

Kishore Kumar Jagadeesha

Devi Sravanthi Yalamarthy

Jonathan Curtis Beard

Geoffray Lacourba

Curtis Glenn Dunham

Antony John Harris

Rishabh Jain

Arthur Brian Laughton

David Joseph Hawkins

Andrew John Turner

Joshua Randall

Lauren Guckert

Guanghui Geng

Pavel Shamis

Premkishore Shivakumar

Sai Kumar Marri

Wenxuan Zhang

Sakshi Verma

Ritukar Khanna

Andrew Brookfield Swaine

Tessil Thomas

Saurabh Pijuskumar Sinha

Zheng Xu

Michael Andrew Campbell

Peter Andrew Riocreux

Alejandro Rico Carro

Roxana Rusitoru

Steven Douglas Krueger

Dam Sunwoo

Jesse Garrett Beu

Timothy Charles Mace

Håkan Lars-Göran Persson

Damien Guillaume Pierre Payet

George Robert Scott Lloyd

Jacob Joseph

Rania Hussein Hassan Mameesh

Andrea Pellegrini

Jeffrey Carl Defilippi

William Henry Flanders

Ho-Seop Kim

Kias Magnus Bruce

Daniel Thomas Pinero

Cesar Aaron Ramirez

Iat Pui Chan

Lakshmi Joga Vishnu Vardhan Badukonda

Glenn Allan Canto

Honnappa Nagarahalli

In response to determining circuitry determining that a portion of data to be sent to a recipient over an interconnect has a predetermined value, data sending circuitry performs data elision to: omit sending at least one data FLIT corresponding to the portion of data having the predetermined value; and send a data-elision-specifying FLIT specifying data-elision information indicating to the recipient that sending of the at least one data FLIT has been omitted and that the recipient can proceed assuming the portion of data has the predetermined value. The data-elision-specifying FLIT is a FLIT other than a write request FLIT for initiating a memory write transaction sequence. This helps to conserve data FLIT bandwidth for other data not having the predetermined value.

Data elision

A technique for handling memory access requests is described. An apparatus has an interconnect for coupling a plurality of requester elements with a plurality of slave elements. The requester elements are arranged to issue memory access requests for processing by the slave elements. An intermediate element within the interconnect acts as a point of serialisation to order the memory access requests issued by requester elements via the intermediate element. The intermediate element has tracking circuitry for tracking handling of the memory access requests accepted by the intermediate element. Further, request acceptance management circuitry is provided to identify a target slave element amongst the plurality of slave elements for that given memory access request, and to determine whether the given memory access request is to be accepted by the intermediate element dependent on an indication of bandwidth capability for the target slave element.

Apparatus and method for handling memory access requests

A super home node of a first chip of a multi-chip data processing system manages coherence for both local and remote cache lines accessed by local caching agents and local cache lines accessed by caching agents of one or more second chips. Both local and remote cache lines are stored in a shared cache, and requests are stored in shared point-of-coherency queue. An entry in a snoop filter table of the super home node includes a presence vector that indicates the presence of a remote cache line at specific caching agents of the first chip or the presence of a local cache line at specific caching agents of the first chip and any caching agent of the second chip. All caching agents of the second chip are represented as a single caching agent in the presence vector.

Data processing network with super home node

There is provided an apparatus, a method, and a storage medium. The apparatus comprises one or more requestor devices to issue transaction requests, and one or more target devices to service those requests. The requestor devices and the target devices are configured to fulfil the requests according to a request ordering protocol specifying an ordered write observation behaviour in which, for each write transaction in a group of ordered write transactions, at least a deferred portion of the write transaction is deferred until all data specified in the group of ordered write transactions preceding the write transaction are observable. When implementing the request ordering protocol, the target devices are responsive to control information taking a first value to dynamically enable the ordered write observation behaviour, and the one or more target devices are responsive to the control information taking a second value to dynamically disable the ordered write observation behaviour.

Transaction requests according to a request ordering protocol

Peripheral components, data processing systems and methods of operating such peripheral components and data processing systems are disclosed. The systems comprise an interconnect comprising a system cache, a peripheral component coupled to the interconnect, and a memory coupled to the interconnect. The peripheral component has a memory access request queue for queuing memory access requests in a receipt order. Memory access requests are issued to the interconnect in the receipt order. A memory read request is not issued to the interconnect until a completion response for all older memory write requests has been received from the interconnect. The peripheral component is responsive to receipt of a memory read request to issue a memory read prefetch request comprising a physical address to the interconnect and the interconnect is responsive to the memory read prefetch request to cause data associated with the physical address in the memory to be cached in the system cache.

Peripheral component handling of memory read requests

Aspects of the present disclosure relate to an apparatus comprising processing circuitry, first cache circuitry and second cache circuitry, wherein the second cache circuitry has an access latency higher than an access latency of the first cache circuitry. The second cache circuitry is responsive to receiving a request for data stored within the second cache circuitry to identify said data as pseudo-invalid data and provide said data to the first cache circuitry. The second cache circuitry is responsive to receiving an eviction indication, indicating that the first cache circuitry is to evict said data, to, responsive to determining that said data has not been modified since said data was provided to the first cache circuitry, identify said pseudo-invalid data as valid data.

Methods and apparatus for transferring data within hierarchical cache circuitry

Data transfer between caching domains of a data processing system is achieved by a local coherency node (LCN) of a first caching domain receiving a read request for data associated with a second caching domain, from a requesting node of the first caching domain. The LCN requests the data from the second caching domain via a transfer agent. In response to receiving a cache line containing the data from the second caching domain, the transfer agent sends the cache line to the requesting node, bypassing the LCN and, optionally, sends a read-receipt indicating the state of the cache line to the LCN. The LCN updates a coherency state for the cache line in response to receiving the read-receipt from the transfer agent and a completion acknowledgement from the requesting node. Optionally, the transfer agent may send the cache line via the LCN when congestion is detected in a response channel of the data processing system.

Method and apparatus for efficient chip-to-chip data transfer

There is provided an apparatus, method, and computer-readable medium. The apparatus comprises interconnect circuitry to couple a device to one or more processing elements and to one or more storage structures. The apparatus also comprises stashing circuitry configured to receive stashing transactions from the device, each stashing transaction comprising payload data and control data. The stashing circuitry is responsive to a given stashing transaction whose control data identifies a plurality of portions of the payload data, to perform a plurality of independent stashing decision operations, each of the plurality of independent stashing decision operations corresponding to a respective portion of the plurality of portions of payload data and comprising determining, with reference to the control data, whether to direct the respective portion to one of the one or more storage structures or whether to forward the respective portion to memory.

Technique for controlling stashing of data

The present disclosure advantageously provides a method and system for transferring data over a chip-to-chip interconnect (CCI). At a request node of a coherent interconnect (CHI) of a first chip, receiving at least one peripheral component interface express (PCIe) transaction from a PCIe master device, the PCIe transaction including a stream identifier; selecting a CCI port of the CHI of the first chip based on the stream identifier of the PCIe transaction; and sending the PCIe transaction to the selected CCI port.

CCIX port management for PCI express traffic

Various implementations described herein are directed to a device with a multi-layered logic structure with multiple layers including a first layer and a second layer arranged vertically in a stacked configuration. The device may have a first cache memory with first interconnect logic disposed in the first layer. The device may have a second cache memory with second interconnect logic disposed in the second layer, wherein the second interconnect logic in the second layer is linked to the first interconnect logic in the first layer.

Multi-dimensional cache architecture

An apparatus and method for handling stash requests are described. The apparatus has a processing element with an associated storage structure that is used to store data for access by the processing element, and an interface for coupling the processing element to interconnect circuitry. Stash request handling circuitry is also provided that, in response to a stash request targeting the storage structure being received at the interface from the interconnect circuitry, causes a block of data associated with the stash request to be stored within the storage structure. The stash request identifies a given address that needs translating into a corresponding physical address in memory, and also identifies an address space key. Address translation circuitry is used to convert the given address identified by the stash request into the corresponding physical address by performing an address translation that is dependent on the address space key identified by the stash request. The stash request handling circuitry is then responsive to the corresponding physical address determined by the address translation circuitry to cause the block of data to be stored at a location within the storage structure associated with the physical address.

Apparatus and method for handling stash requests

The present disclosure advantageously provides a system cache and a method for storing coherent data and non-coherent data in a system cache. A transaction is received from a source in a system, the transaction including at least a memory address, the source having a location in a coherent domain or a non-coherent domain of the system, the coherent domain including shareable data and the non-coherent domain including non-shareable data. Whether the memory address is stored in a cache line is determined, and, when the memory address is not determined to be stored in a cache line, a cache line is allocated to the transaction including setting a state bit of the allocated cache line based on the source location to indicate whether shareable or non-shareable data is stored in the allocated cache line, and the transaction is processed.

Cache for storing coherent and non-coherent data

A request node is provided comprising request circuitry to issue write requests to write data to storage circuitry. The write requests are issued to the storage circuitry via a coherency node. Status receiving circuitry receives a write status regarding write operations at the storage circuitry from the coherency node and throttle circuitry throttles a rate at which the write requests are issued to the storage circuitry in dependence on the write status. A coherency node is also provided, comprising access circuitry to receive a write request from a request node to write data to storage circuitry and to access the storage circuitry to write the data to the storage circuitry. Receive circuitry receives, from the storage circuitry, an incoming write status regarding write operations at the storage circuitry and transmit circuitry transmits an outgoing write status to the request node based on the incoming write status.

Write operation status

Aspects of the present disclosure relate to an interconnect comprising interfaces to communicate with respective requester and receiver node devices, and home nodes. Each home node is configured to: receive requests from one or more requester nodes, each request comprising a target address corresponding to a target receiver nodes; and transmit each said request to the corresponding target receiver node. Mapping circuitry is configured to: associate each of said plurality of home nodes with a given home node cluster; perform a first hashing of the target address of a given request, to determine a target cluster; perform a second hashing of the target address, to determine a target home node within said target cluster; and direct the given message, to the target home node.

Methods and apparatus for communicating between node devices

An apparatus comprises snoop filter storage circuitry to store snoop filter entries corresponding to addresses and comprising sharer information. Control circuitry selects which sharers, among a plurality of sharers capable of holding cached data, should be issued with snoop requests corresponding to a target address, based on the sharer information of the snoop filter entry corresponding to the target address. The control circuitry is capable of setting a given snoop filter entry corresponding to a given address to an imprecise encoding in which the sharer information provides an imprecise description of which sharers hold cached data corresponding to the given address, and the given snoop filter entry comprises at least one sharer count value indicative of a number of sharers holding cached data corresponding to the given address.

Snoop filter with imprecise encoding

Growing community of inventors

Austin, TX, United States of America

Jamshed Jalal