Abstract: Statistical data is used to enable or disable snooping on a bus of a processor. A command is received via a first bus or a second bus communicably coupling processor cores and caches of chiplets on the processor. Cache logic on a chiplet determines whether or not a local cache on the chiplet can satisfy a request for data specified in the command. In response to determining that the local cache can satisfy the request for data, the cache logic updates statistical data maintained on the chiplet. The statistical data indicates a probability that the local cache can satisfy a future request for data. Based at least in part on the statistical data, the cache logic determines whether to enable or disable snooping on the second bus by the local cache.

Abstract: In a multithreaded data processing system including a plurality of processor cores, storage-modifying and synchronization requests of a plurality of concurrently executing hardware threads are received in a shared queue. The plurality of storage-modifying requests includes a translation invalidation request of an initiating hardware thread, and the synchronization requests includes a synchronization request of the initiating hardware thread. The translation invalidation request is broadcast such that the translation invalidation request is received and processed by the plurality of processor cores to invalidate any translation entry that translates a target address of the translation invalidation request.

Abstract: Accessing partial cachelines in a data cache including storing a first portion of a cacheline in a cache entry of the data cache; relaunching a load instruction targeting a second portion of the cacheline, wherein the second portion of the cacheline is not stored in the data cache; determining that the load instruction targets a portion of the cacheline not stored in the cache entry; storing the second portion of the cacheline in the data cache; and reading the second portion of the cacheline from the data cache according to the load instruction.

Abstract: In at least some embodiments, a processor core generates a store operation by executing a store instruction in an instruction sequence. The store operation is marked as a high priority store operation operation in response to detecting, in the instruction sequence, a barrier instruction that precedes the store instruction in program order and that includes a field set to indicate the store operation should be accorded high priority and is not so marked otherwise. The store operation is buffered in a store queue associated with a cache memory of the processor core. Handling of the store operation in the store queue is expedited in response to the store operation being marked as a high priority store operation and not expedited otherwise.

Abstract: In at least some embodiments, a processor core generates a store operation by executing a store instruction in an instruction sequence. The store operation is marked as a high priority store operation in response to detecting, in the instruction sequence, a barrier instruction that precedes the store instruction in program order and that includes a field set to indicate the store operation should be accorded high priority and is not so marked otherwise. The store operation is buffered in a store queue associated with a cache memory of the processor core. Handling of the store operation in the store queue is expedited in response to the store operation being marked as a high priority store operation and not expedited otherwise.

Abstract: A technique for operating a lower level cache memory of a data processing system includes receiving an operation that is associated with a first thread. Logical partition (LPAR) information for the operation is used to limit dependencies in a dependency data structure of a store queue of the lower level cache memory that are set and to remove dependencies that are otherwise unnecessary.

Abstract: A technique for operating a lower level cache memory of a data processing system includes receiving, by a store queue controller, an operation that is associated with a first thread. The store queue controller uses level one (L1) cache memory miss information for the operation to limit dependencies in a dependency data structure of a store queue of the lower level cache memory that are set and to remove dependencies that are otherwise unnecessary.

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: In at least one embodiment, a multiprocessor data processing system includes multiple vertical cache hierarchies supporting a plurality of processor cores, a system memory, and an interconnect fabric. In response to a first cache memory snooping on the interconnect fabric a request of an interconnect operation of a second cache memory, the first cache memory allocates a snoop machine to service the request. Responsive to the snoop machine completing its processing of the request and prior to the first cache memory receiving a systemwide coherence response of the interconnect operation, the first cache memory allocates an entry in a data structure to handle completion of processing for the interconnection operation and deallocates the snoop machine. The entry of the data structure protects transfer of coherence ownership of a target cache line from the first cache memory to the second cache memory during a protection window extending at least until the systemwide coherence response is received.

Abstract: A multiprocessor data processing system includes multiple vertical cache hierarchies supporting a plurality of processor cores, a system memory, and a system interconnect. In response to a load-and-reserve request from a first processor core, a first cache memory supporting the first processor core issues on the system interconnect a memory access request for a target cache line of the load-and-reserve request. Responsive to the memory access request and prior to receiving a systemwide coherence response for the memory access request, the first cache memory receives from a second cache memory in a second vertical cache hierarchy by cache-to-cache intervention the target cache line and an early indication of the systemwide coherence response for the memory access request. In response to the early indication and prior to receiving the systemwide coherence response, the first cache memory initiating processing to update the target cache line in the first cache memory.

Abstract: A multiprocessor data processing system includes multiple vertical cache hierarchies supporting a plurality of processor cores, a system memory, and a system interconnect coupled to the system memory and the multiple vertical cache hierarchies. A first cache memory in a first vertical cache hierarchy issues on the system interconnect a request for a target cache line. Responsive to the request and prior to receiving a systemwide coherence response for the request, the first cache memory receives from a second cache memory in a second vertical cache hierarchy by cache-to-cache intervention the target cache line and an early indication of the systemwide coherence response for the request. In response to the early indication of the systemwide coherence response and prior to receiving the systemwide coherence response, the first cache memory initiates processing to install the target cache line in the first cache memory.

Abstract: In a multithreaded data processing system including a plurality of processor cores, storage-modifying requests, including a translation invalidation request of an initiating hardware thread, are received in a shared queue. The translation invalidation request is broadcast so that it is received and processed by the plurality of processor cores. In response to confirmation of the broadcast, the address translated by the translation entry is stored in a queue. Once the address is stored, the initiating processor core resumes dispatch of instructions within the initiating hardware thread. In response to a request from one of the plurality of processor cores, an effective address translated by a translation entry being invalidated is accessed in the queue. A synchronization request for the address is broadcast to ensure completion of processing of any translation invalidation request for the address.

Abstract: In at least some embodiments, a processor core executes a sending thread including a first push instruction and a second push instruction subsequent to the first push instruction in a program order. Each of the first and second push instructions requests that a respective message payload be pushed to a mailbox of a receiving thread. In response to executing the first and second push instructions, the processor core transmits respective first and second co-processor requests to a switch in the data processing system via an interconnect fabric of the data processing system. The processor core transmits the second co-processor request to the switch without regard to acceptance of the first co-processor request by the switch.

Abstract: In a multithreaded data processing system including a plurality of processor cores, storage-modifying requests, including a translation invalidation request of an initiating hardware thread, are received in a shared queue. The translation invalidation request is broadcast so that it is received and processed by the plurality of processor cores. In response to confirmation of the broadcast, the address translated by the translation entry is stored in a queue. Once the address is stored, the initiating processor core resumes dispatch of instructions within the initiating hardware thread. In response to a request from one of the plurality of processor cores, an effective address translated by a translation entry being invalidated is accessed in the queue. A synchronization request for the address is broadcast to ensure completion of processing of any translation invalidation request for the address.

Abstract: In at least some embodiments, a processor core executes a sending thread including a first push instruction and a second push instruction subsequent to the first push instruction in a program order. Each of the first and second push instructions requests that a respective message payload be pushed to a mailbox of a receiving thread. In response to executing the first and second push instructions, the processor core transmits respective first and second co-processor requests to a switch in the data processing system via an interconnect fabric of the data processing system. The processor core transmits the second co-processor request to the switch without regard to acceptance of the first co-processor request by the switch.

Abstract: A data processing system includes an upper level cache memory and a lower level cache memory employing different replacement policies. The lower level cache memory provides a respective one of a plurality of counters for each of a plurality of cache lines in a particular congruence class. The lower level cache memory initializes a counter value for a cache line in the particular congruence class that was castout from the upper level cache memory based on an indication of whether the cache line was accessed in the upper level cache memory following installation in the upper level cache memory. The lower level cache memory selects a victim cache line from among the plurality of cache lines in the particular congruence class for eviction from the lower level cache memory by reference to counter values of the plurality of counters.

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 multithreaded data processing system including a plurality of processor cores, storage-modifying requests, including a translation invalidation request of an initiating hardware thread, are received in a shared queue. The translation invalidation request is removed and buffered in sidecar logic. While the translation invalidation request is buffered in the sidecar logic, the sidecar logic broadcasts the translation invalidation request so that it is received and processed by the plurality of processor cores. In response to confirmation of completion of processing of the translation invalidation request by the initiating processor core, the sidecar logic removes the translation invalidation request from the sidecar. Completion of processing of the translation invalidation request at all of the plurality of processor cores is ensured by a broadcast synchronization request.