Abstract: A set-associative cache memory includes a plurality of congruence classes each including multiple entries for storing cache lines of data. A respective one of a plurality of counters is maintained for each cache line stored in the multiple entries. In response to a memory access request, the cache memory selects a victim cache line stored in a particular entry of a particular congruence class for eviction from the cache memory by reference to at least a counter value of the victim cache line. The cache memory also receives a new cache line of data for insertion into the particular entry and an indication of a distance from the cache memory to a data source from which the cache memory received the new cache line. The cache memory installs the new cache line in the particular entry and sets an initial counter value of the counter for the new cache line based on the received indication of the distance.

Abstract: A set-associative cache memory includes a plurality of congruence classes each including multiple entries for storing cache lines of data. A respective one of a plurality of counters is maintained for each cache line stored in the multiple entries. In response to a memory access request, the cache memory selects a victim cache line stored in a particular entry of a particular congruence class for eviction from the cache memory by reference to at least a counter value of the victim cache line. The cache memory also receives a new cache line of data for insertion into the particular entry and an indication of a coherence state of the new cache line at a data source from which the cache memory received the new cache line. The cache memory installs the new cache line in the particular entry and sets an initial counter value of the counter for the new cache line based on the received indication of the coherence state at the data source.

Abstract: In a data processing system, a switch includes a receive data structure including receive entries each uniquely corresponding to a receive window, where each receive entry includes addressing information for one or more mailboxes into which messages can be injected, a send data structure including send entries each uniquely corresponding to a send window, where each send entry includes a receive window field that identifies one or more receive windows, and switch logic. The switch logic, responsive to a request to push a message to one or more receiving threads, accesses a send entry that corresponds to a send window of the sending thread, utilizes contents of the receive window field of the send entry to access one or more of the receive entries, and pushes the message to one or more mailboxes of one or more receiving threads utilizing the addressing information of the receive entry or entries.

Abstract: In a data processing system, a switch includes a receive data structure including receive entries each uniquely corresponding to a receive window, where each receive entry includes addressing information for one or more mailboxes into which messages can be injected, a send data structure including send entries each uniquely corresponding to a send window, where each send entry includes a receive window field that identifies one or more receive windows, and switch logic. The switch logic, responsive to a request to push a message to one or more receiving threads, accesses a send entry that corresponds to a send window of the sending thread, utilizes contents of the receive window field of the send entry to access one or more of the receive entries, and pushes the message to one or more mailboxes of one or more receiving threads utilizing the addressing information of the receive entry or entries.

Abstract: According to a method of data processing, a memory controller receives a plurality of data prefetch requests from multiple processor cores in the data processing system, where the plurality of prefetch load requests include a data prefetch request issued by a particular processor core among the multiple processor cores. In response to receipt of the data prefetch request, the memory controller provides a coherency response indicating an excess number of data prefetch requests. In response to the coherency response, the particular processor core reduces a rate of issuance of data prefetch requests.

Abstract: A processor core of a data processing system receives a push instruction of a sending thread that requests that a message payload identified by at least one operand of the push instruction be pushed to a mailbox of a receiving thread. In response to receiving the push instruction, the processor core executes the push instruction of the sending thread. In response to executing the push instruction, the processor core initiates transmission of the message payload to the mailbox of the receiving thread. In one embodiment, the processor core initiates transmission of the message payload by transmitting a co-processor request to a switch of the data processing system via an interconnect fabric.

Abstract: A technique for operating a cache memory of a data processing system includes creating respective pollution vectors to track which of multiple concurrent threads executed by an associated processor core are currently polluted by a store operation resident in the cache memory. Dependencies in a dependency data structure of a store queue of the cache memory are set based on the pollution vectors to reduce unnecessary ordering effects. Store operations are dispatched from the store queue in accordance with the dependencies indicated by the dependency data structure.

Abstract: A processor core of a data processing system receives a push instruction of a sending thread that requests that a message payload identified by at least one operand of the push instruction be pushed to a mailbox of a receiving thread. In response to receiving the push instruction, the processor core executes the push instruction of the sending thread. In response to executing the push instruction, the processor core initiates transmission of the message payload to the mailbox of the receiving thread. In one embodiment, the processor core initiates transmission of the message payload by transmitting a co-processor request to a switch of the data processing system via an interconnect fabric.

Abstract: A technique for operating a cache memory of a data processing system includes creating respective pollution vectors to track which of multiple concurrent threads executed by an associated processor core are currently polluted by a store operation resident in the cache memory. Dependencies in a dependency data structure of a store queue of the cache memory are set based on the pollution vectors to reduce unnecessary ordering effects. Store operations are dispatched from the store queue in accordance with the dependencies indicated by the dependency data structure.

Abstract: In at least some embodiments, a cache memory of a data processing system receives a transactional memory access request including a target address and a priority of the requesting memory transaction. In response, transactional memory logic detects a conflict for the target address with a transaction footprint of an existing memory transaction and accesses a priority of the existing memory transaction. In response to detecting the conflict, the transactional memory logic resolves the conflict by causing the cache memory to fail the requesting or existing memory transaction based at least in part on their relative priorities. Resolving the conflict includes at least causing the cache memory to fail the existing memory transaction when the requesting memory transaction has a higher priority than the existing memory transaction, the transactional memory access request is a transactional load request, and the target address is within a store footprint of the existing memory transaction.

Abstract: In at least some embodiments, a cache memory of a data processing system receives a transactional memory access request including a target address and a priority of the requesting memory transaction. In response, transactional memory logic detects a conflict for the target address with a transaction footprint of an existing memory transaction and accesses a priority of the existing memory transaction. In response to detecting the conflict, the transactional memory logic resolves the conflict by causing the cache memory to fail the requesting or existing memory transaction based at least in part on their relative priorities. Resolving the conflict includes at least causing the cache memory to fail the existing memory transaction when the requesting memory transaction has a higher priority than the existing memory transaction, the transactional memory access request is a transactional load request, and the target address is within a store footprint of the existing memory transaction.

Abstract: A computer system comprises a processor unit arranged to run a hypervisor running one or more virtual machines, a cache connected to the processor unit and comprising a plurality of cache rows, each cache row comprising a memory address, a cache line and an image modification flag and a memory connected to the cache and arranged to store an image of at least one virtual machine. The processor unit is arranged to define a log in the memory and the cache further comprises a cache controller arranged to set the image modification flag for a cache line modified by a virtual machine being backed up, periodically check the image modification flags and write only the memory address of the flagged cache rows in the defined log. The processor unit is further arranged to monitor the free space available in the defined log and to trigger an interrupt if the free space available falls below a specific amount.

Abstract: A technique for operating a cache memory of a data processing system includes creating respective pollution vectors to track which of multiple concurrent threads executed by an associated processor core are currently polluted by a store operation resident in the cache memory. Dependencies in a dependency data structure of a store queue of the cache memory are set based on the pollution vectors to reduce unnecessary ordering effects. Store operations are dispatched from the store queue in accordance with the dependencies indicated by the dependency data structure.

Abstract: In response to a transactional store request, the higher level cache transmits, to the lower level cache, a backup copy of an unaltered target cache line in response to a target real address hitting in the higher level cache, updates the target cache line with store data to obtain an updated target cache line, and records the target real address as belonging to a transaction footprint of the memory transaction. In response to a conflicting access to the transaction footprint prior to completion of the memory transaction, the higher level cache signals failure of the memory transaction to the processor core, invalidates the updated target cache line in the higher level cache, and causes the backup copy of the target cache line in the lower level cache to be restored as a current version of the target cache line.

Abstract: In response to a transactional store request, the higher level cache transmits, to the lower level cache, a backup copy of an unaltered target cache line in response to a target real address hitting in the higher level cache, updates the target cache line with store data to obtain an updated target cache line, and records the target real address as belonging to a transaction footprint of the memory transaction. In response to a conflicting access to the transaction footprint prior to completion of the memory transaction, the higher level cache signals failure of the memory transaction to the processor core, invalidates the updated target cache line in the higher level cache, and causes the backup copy of the target cache line in the lower level cache to be restored as a current version of the target cache line.

Abstract: In one or more embodiments, one or more systems, devices, methods, and/or processes described can send, via an interconnect, a rate master command to at least one of multiple processing nodes; determine that a message indicating a dropped command, associated with the rate master command, is received; determine that a count, associated with dropped commands, satisfies a threshold; and provide, to the processing nodes via the interconnect, a signal indicating a command rate, in response to determining that the count satisfies the threshold. Moreover, the count can be incremented in response to determining that the message is received. The at least one of multiple processing nodes can receive, via the interconnect, the signal indicating the command rate and can utilize the command rate in issuing speculative commands, via the interconnect.

Abstract: In one or more embodiments, one or more systems, devices, methods, and/or processes described can send, via an interconnect, a rate master command to at least one of multiple processing nodes; determine that a message indicating a dropped command, associated with the rate master command, is received; determine that a count, associated with dropped commands, satisfies a threshold; and provide, to the processing nodes via the interconnect, a signal indicating a command rate, in response to determining that the count satisfies the threshold. Moreover, the count can be incremented in response to determining that the message is received. The at least one of multiple processing nodes can receive, via the interconnect, the signal indicating the command rate and can utilize the command rate in issuing speculative commands, via the interconnect.

Abstract: In a data processing system, a memory subsystem detects whether or not at least one potentially transient condition is present that would prevent timely servicing of one or more memory access requests directed to the associated system memory. In response to detecting at least one such potentially transient condition, the memory system identifies a first read request affected by the at least one potentially transient condition. In response to identifying the read request, the memory subsystem signals to a request source to issue a second read request for the same target address by transmitting to the request source dummy data and a data error indicator.

Abstract: An integrated circuit system including a first integrated circuit chip including first logic, a second integrated circuit chip, and second logic distributed across the first and second integrated circuit chips. The second logic includes a first unit integrated in the first integrated circuit chip and a second unit integrated in the second integrated circuit chip. The integrated circuit system further includes a physical communication link coupling the first unit in the first integrated circuit chip and the second unit in the second integrated circuit chip and a request interface between the first logic and first unit of the second logic. The request interface is implemented in the first integrated circuit such that communication via the request interface between the first logic and the first unit of the second logic has low latency and such that the request interface is decoupled from the physical communication link.

Abstract: A coherent attached processor proxy (CAPP) within a primary coherent system participates in an operation on a system fabric of the primary coherent system on behalf of an attached processor (AP) that is external to the primary coherent system and that is coupled to the CAPP. The operation includes multiple components communicated with the CAPP including a request and at least one coherence message. The CAPP determines one or more of the components of the operation by reference to at least one programmable data structure within the CAPP that can be reprogrammed.