Arm Limited

Other

Andrew John Turner

Alex James Waugh

Klas Magnus Bruce

Geoffray Lacourba

Michael Alexander Kennedy

Simon John Craske

Jamshed Jalal

Fergus Wilson MacGarry

Richard Anthony Lane

Rania Hussein Hassan Mameesh

Yew Keong Chong

Andy Wangkun Chen

Bruce James Mathewson

Sriram Thyagarajan

Matthew Lucien Evans

Phanindra Kumar Mannava

Joseph Michael Pusdesris

Vivek Asthana

Gurunath Ramagiri

Sergio Schuler

Shobhit Singhal

Adam James McNeeney

Munish Kumar

Martin Weidmann

Dimitrios Kaseridis

Timothy Nicholas Hay

Devin S Lafford

Anthony Jebson

Gareth James Evans

Ho-Seop Kim

There is provided an apparatus, a method, a system, a chip containing product, and a medium. The apparatus comprises a first storage structure to store a first set of data items, the first storage structure comprising a first transaction queue to store first transaction data to track fulfilment of outstanding first transaction requests. The apparatus is also provided with a second storage structure. The first storage structure is responsive to a received request for a given data item, to issue a first transaction request for the given data item to the second storage structure, and for a stage of fulfilment of the first transaction request, to omit storage of information relating to the first transaction request in the first transaction queue and to delegate the maintenance of at least some information relating to the stage of fulfilment of the first transaction request to the second storage structure.

Fulfilment of transaction requests

A memory instance comprises a plurality of banks of storage cells to store data values, and input/output circuitry shared between the plurality of banks for receiving write data or outputting read data. Each bank of storage cells supports a power saving mode and an operational mode. A control interface receives power control signals for controlling use of the power saving mode. Bank power control circuitry individually controls, for each of a plurality of subsets of banks of storage cells within the same memory instance, whether that subset of banks is in the power saving mode based on the power control signals. For at least one setting for the power control signals, one subset of banks is in the power saving mode while another subset of banks in the same memory instance is in the operational mode. Also disclosed is power control circuitry which selects the power mode to use for each subset of banks and generates the power control signals.

Power saving mode control for a memory instance

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

An apparatus and method for operating a ring interconnect are disclosed. The ring interconnect has a plurality of nodes that are used to connect to associated components, and is arranged to transport a plurality of slots around the ring interconnect between the nodes in order to transfer items of traffic allocated into those slots between components connected to the nodes. For each item of traffic, one of the components acts as a source to allocate that item of traffic into a slot, and another components acts as destination to seek to remove that item of traffic from the slot. In a default mode of operation, the ring interconnect is arranged to allow all of the slots to be available for transfer of any items of traffic. Special slot management circuitry is provided that is responsive to a throughput alert trigger indicating a potential for occurrence of a throughput inhibiting condition, to cause a slot amongst the plurality of slots to be reserved as a special slot that is constrained for use only when one or more determined conditions are met. Further, the one or more determined conditions are arranged to cause the special slot to be used in a manner that seeks to avoid the throughput inhibiting condition arising.

Apparatus and method for operating a ring interconnect

A ring interconnect system comprises a plurality of nodes. Each node is connected to two other nodes to form a ring interconnect. Every pair of nodes is connected by an inter-node path for that pair of nodes distinct from the ring interconnect. Each of the nodes comprises a message buffer to buffer messages received from at least one device associated with the node. Each of the nodes also comprises activity level circuitry to transmit an activity indication, when a number of the messages in the message buffer is equal to or above a threshold, to each other node of the plurality of nodes via the respective inter-node paths. Each of the nodes also comprises arbitrator circuitry to receive the activity indications from each other node and from the activity level circuitry, and to allow ingress of a message from the message buffer onto the ring interconnect in dependence on the activity indications. Also provided is a method of operating a node of a ring interconnect system.

Message arbitration in a ring interconnect system based on activity indications for each node in the ring interconnect

An interrupt controller comprises issue circuitry to issue interrupt requests to a processing element and control circuitry to detect presence of a race condition in association with at least one pending interrupt request to be issued, and to set a barrier indicator when the race condition has been resolved. In response to the race condition being present, the issue circuitry is configured to select one of the at least one pending interrupt requests, to issue to the processing element the selected pending interrupt request followed by a dummy request over a path that ensures that the processing element receives the selected pending interrupt request prior to receiving the dummy request. On receiving an acknowledgement indicating that the processing element has received the dummy request, the control circuitry is then configured to set the barrier indicator.

Interrupt controller

Circuitry comprises a set of two or more data handling nodes each having respective storage circuitry to hold data; and a home node to serialise data access operations and to control coherency amongst data held by the one or more data handling nodes so that data written to a memory address is consistent with data read from that memory address in response to a subsequent access request; in which: a requesting node of the set of data handling nodes is configured to communicate a request to the home node for exclusive access to a given instance of data at a given memory address; and the home node is configured, in response to the request, to communicate information to other data handling nodes of the set of data handling nodes to control handling, by those other data handling nodes, of any further instances of the data at the given memory address which are held by those other data handling nodes.

Exclusivity in circuitry having a home node providing coherency control

Circuitry comprises a data store to hold status data indicating a status of a first set of one or more devices connected to the interconnect circuitry; and control circuitry, responsive to initiation of a data handling transaction, to generate recovery data indicative of an initial state of the status data and to predict a predicted revised state of the status data applicable to resolution of the data handling transaction; the control circuitry being configured to change the status data to the predicted revised state in response to initiation of the transaction and before resolution of the transaction, and in response to a request to access the status data between the change of the status data to the predicted revised state and the resolution of the transaction, to provide access to the initial state of the status data, using the recovery data.

Generating recovery data for an initial state of status data for a data handling transaction and predicting a revised state of the status data applicable to resolution of the data handling transaction

An interconnect apparatus comprises first node circuitry for performing first node operations to service data access requests in respect of a first range of memory addresses and second node circuitry for performing second node operations to service data access requests in respect of a second range of memory addresses. The interconnect comprises interface circuitry to: receive a retry indication in respect of a data access request from the first node and forward the retry indication to the requester circuitry; responsive to determining that the interface circuitry has capacity for the data access request, transmit a reissue capacity message to the requester circuitry; receive a reissued data access request from the requester circuitry; and issue the reissued data access request to the second node circuitry. The second node circuitry is responsive to receiving the reissued data access request to service the data access request.

Methods and apparatus for reconfiguring nodes and reissuing data access requests

Aspects of the present disclosure relate to an interconnect comprising an interface to couple to a master device, the interface comprising buffer storage. The interface is configured to receive a request from the master device for data comprising a plurality of data blocks, the master device requiring the data blocks in a defined order. A data collator is configured to: receive the request; issue a data pull request to cause the interface to allocate buffer space in the buffer storage for buffering the requested data; and responsive to receiving a confirmation that the buffer space is allocated, provide the requested data to the buffer storage. The interface is configured to employ the buffer storage to enable re-ordering of the plurality of data blocks of the requested data, prior to outputting the plurality of data blocks to the master device; and output the plurality of data blocks to the master device in the defined order.

Apparatus and method for providing data to a master device

A data processing system includes an interrupt controller having a priority level arbitrator and trigger circuitry. The priority level arbitrator and the trigger circuitry operate in parallel to process interrupt signals received by an interrupt signal receiver. The trigger circuitry generates a trigger signal initiating interrupt processing before the priority level arbitrator has completed its arbitration determination at an arbitration-completed time. If the interrupt processing triggered by the trigger signal was inappropriate, then is terminated once the result of the arbitration is known after the arbitration-completed time.

Speculative interrupt signalling

An interrupt controller includes a priority level arbitrator () including multiple stages. The stages include at least one stage comprising a plurality of interrupt selectors formed of a multiplexer () for selecting between a pair of potentially concurrently asserted interrupt signals in dependence upon selection data. The selection data is determined in advance by a priority level comparator () using priority level data associated with the respective interrupt signals.

Interrupt signal arbitration

An interrupt controller for controlling the routing and handling of interrupts received at a data processing apparatus including at least one physical processing unit configured to run at least one of a plurality of virtual processors and a memory. The interrupt controller includes redistribution circuitry with at least one data store corresponding to the unit, the data store storing a pointer to a virtual pending table storing currently pending virtual interrupts for a virtual processor currently running on the corresponding unit and a pointer to a pending table configured to store currently pending physical interrupts for the corresponding unit and an input configured to receive a virtual interrupt for interrupting a virtual processor. Control circuitry is configured to add the virtual interrupt to the virtual pending table and to store the virtual interrupt in the virtual pending table for the virtual processor that is stored in the memory.

Handling and routing interrupts to virtual processors

A positioning device () for producing a light signal () to position a robot tool () relative to a workpiece () is provided. The positioning device () comprises a frame () and a pair of light sources () mounted at the free end of the frame and arranged to direct a pair of light beams () therefrom in converging directions which intersect with each other and provide a light signal () at a predetermined distance from the free end of the frame (). The positioning device () can include two pairs of light sources to generate two pairs of intersecting light beams (). The two pairs of light sources can be arranged so that the two pairs of light beams () are located substantially 90 degrees apart.

Growing community of inventors

Cambridge, United Kingdom

Andrew John Turner