Abstract: In one or more embodiments, one or more systems, devices, methods, and/or processes described can continually increase a command rate of an interconnect if one or more requests to lower the command rate are not received within one or more periods of time. In one example, the command rate can be set to a fastest level. In another example, the command rate can be incrementally increased over periods of time. If a request to lower the command rate is received, the command rate can be set to a reference level or can be decremented to one slower rate level. In one or more embodiments, the one or more requests to lower the command rate can be based on at least one of an issue rate of speculative commands and a number of overcommit failures, among others.

Abstract: In a data processing system having a processor core and a shared memory system including a cache memory that supports the processor core, a transactional memory access request is issued by the processor core in response to execution of a memory access instruction in a memory transaction undergoing execution by the processor core. In response to receiving the transactional memory access request, dispatch logic of the cache memory evaluates the transactional memory access request for dispatch, where the evaluation includes determining whether the memory transaction has a failing transaction state. In response to determining the memory transaction has a failing transaction state, the dispatch logic refrains from dispatching the memory access request for service by the cache memory and refrains from updating at least replacement order information of the cache memory in response to the transactional memory access request.

Abstract: In a data processing system having a processor core and a shared memory system including a cache memory that supports the processor core, a transactional memory access request is issued by the processor core in response to execution of a memory access instruction in a memory transaction undergoing execution by the processor core. In response to receiving the transactional memory access request, dispatch logic of the cache memory evaluates the transactional memory access request for dispatch, where the evaluation includes determining whether the memory transaction has a failing transaction state. In response to determining the memory transaction has a failing transaction state, the dispatch logic refrains from dispatching the memory access request for service by the cache memory and refrains from updating at least replacement order information of the cache memory in response to the transactional memory access request.

Abstract: A virtual machine backup method includes utilizing a log to indicate updates to memory of a virtual machine when the updates are evicted from a cache of the virtual machine. A guard band is determined that indicates a threshold amount of free space for the log. A determination is made that the guard band will be or has been encroached upon corresponding to indicating an update in the log. A backup image of the virtual machine is updated based, at least in part, on a set of one or more entries of the log, wherein the set of entries is sufficient to comply with the guard band. The set of entries is removed from the log.

Abstract: A technique for operating a memory system for a node includes interrogating, by a cache, an associated cache directory to determine whether a shared cache line to be installed in the cache is associated with an invalid global state in the cache. The invalid global state specifies that a version of the shared cache line has been intervened off-node. In response to the shared cache line being in the invalid global state the cache spawns a castout invalid global command for the shared cache line. The shared cache line is installed in the cache. A coherence state for the shared cache line is updated in the associated cache directory to indicate the shared cache line is shared.

Abstract: A technique for operating a memory system for a node includes interrogating, by a cache, an associated cache directory to determine whether a shared cache line to be installed in the cache is associated with an invalid global state in the cache. The invalid global state specifies that a version of the shared cache line has been intervened off-node. In response to the shared cache line being in the invalid global state the cache spawns a castout invalid global command for the shared cache line. The shared cache line is installed in the cache. A coherence state for the shared cache line is updated in the associated cache directory to indicate the shared cache line is shared.

Abstract: In response to execution in a memory transaction of a transactional load instruction that speculatively binds to a value held in a store-through upper level cache, a processor core sets a flag, transmits a transactional load operation to a store-in lower level cache that tracks a target cache line address of a target cache line containing the value, monitors, during a core TM tracking interval, the target cache line address for invalidation messages from the store-in lower level cache until the store-in lower level cache signals that the store-in lower level cache has assumed responsibility for tracking the target cache line address, and responsive to receipt during the core TM tracking interval of an invalidation message indicating presence of a conflicting snooped operation, resets the flag. At termination of the memory transaction, the processor core fails the memory transaction responsive to the flag being reset.

Abstract: In response to execution in a memory transaction of a transactional load instruction that speculatively binds to a value held in a store-through upper level cache, a processor core sets a flag, transmits a transactional load operation to a store-in lower level cache that tracks a target cache line address of a target cache line containing the value, monitors, during a core TM tracking interval, the target cache line address for invalidation messages from the store-in lower level cache until the store-in lower level cache signals that the store-in lower level cache has assumed responsibility for tracking the target cache line address, and responsive to receipt during the core TM tracking interval of an invalidation message indicating presence of a conflicting snooped operation, resets the flag. At termination of the memory transaction, the processor core fails the memory transaction responsive to the flag being reset.

Abstract: A data processing system includes first and second processing units and a system memory. The first processing unit has first upper and first lower level caches, and the second processing unit has second upper and lower level caches. In response to a data request, a victim cache line to be castout from the first lower level cache is selected, and the first lower level cache selects between performing a lateral castout (LCO) of the victim cache line to the second lower level cache and a castout of the victim cache line to the system memory based upon a confidence indicator associated with the victim cache line. In response to selecting an LCO, the first processing unit issues an LCO command on the interconnect fabric and removes the victim cache line from the first lower level cache, and the second lower level cache holds the victim cache line.

Abstract: A data processing system includes first and second processing units and a system memory. The first processing unit has first upper and first lower level caches, and the second processing unit has second upper and lower level caches. In response to a data request, a victim cache line to be castout from the first lower level cache is selected, and the first lower level cache selects between performing a lateral castout (LCO) of the victim cache line to the second lower level cache and a castout of the victim cache line to the system memory based upon a confidence indicator associated with the victim cache line. In response to selecting an LCO, the first processing unit issues an LCO command on the interconnect fabric and removes the victim cache line from the first lower level cache, and the second lower level cache holds the victim cache line.

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 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: 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 at least some embodiments, a cache memory of a data processing system receives a speculative memory access request including a target address of data speculatively requested for a processor core. In response to receipt of the speculative memory access request, transactional memory logic determines whether or not the target address of the speculative memory access request hits a store footprint of a memory transaction. In response to determining that the target address of the speculative memory access request hits a store footprint of a memory transaction, the transactional memory logic causes the cache memory to reject servicing the speculative memory access request.

Abstract: In some embodiments, in response to execution of a load-reserve instruction that binds to a load target address held in a store-through upper level cache, a processor core sets a core reservation flag, transmits a load-reserve operation to a store-in lower level cache, and tracks, during a core reservation tracking interval, the reservation requested by the load-reserve operation until the store-in lower level cache signals that the store-in lower level cache has assumed responsibility for tracking the reservation. In response to receipt during the core reservation tracking interval of an invalidation signal indicating presence of a conflicting snooped operation, the processor core cancels the reservation by resetting the core reservation flag and fails a subsequent store-conditional operation.

Abstract: In some embodiments, in response to execution of a load-reserve instruction that binds to a load target address held in a store-through upper level cache, a processor core sets a core reservation flag, transmits a load-reserve operation to a store-in lower level cache, and tracks, during a core reservation tracking interval, the reservation requested by the load-reserve operation until the store-in lower level cache signals that the store-in lower level cache has assumed responsibility for tracking the reservation. In response to receipt during the core reservation tracking interval of an invalidation signal indicating presence of a conflicting snooped operation, the processor core cancels the reservation by resetting the core reservation flag and fails a subsequent store-conditional operation.

Abstract: In at least some embodiments, a cache memory of a data processing system receives a speculative memory access request including a target address of data speculatively requested for a processor core. In response to receipt of the speculative memory access request, transactional memory logic determines whether or not the target address of the speculative memory access request hits a store footprint of a memory transaction. In response to determining that the target address of the speculative memory access request hits a store footprint of a memory transaction, the transactional memory logic causes the cache memory to reject servicing the speculative memory access request.

Abstract: In response to a memory access request of a processor core that targets a target cache line, the lower level cache of a vertical cache hierarchy associated with the processor core supplies a copy of the target cache line to an upper level cache in the vertical cache hierarchy and retains a copy in a shared coherence state. The upper level cache holds the copy of the target cache line in a private shared ownership coherence state indicating that each cached copy of the target memory block is cached within the vertical cache hierarchy associated with the processor core. In response to the upper level cache signaling replacement of the copy of the target cache line in the private shared ownership coherence state, the lower level cache updates its copy of the target cache line to the exclusive ownership coherence state without coherency messaging with other vertical cache hierarchies.

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 one or more embodiments, one or more systems, devices, methods, and/or processes described can continually increase a command rate of an interconnect if one or more requests to lower the command rate are not received within one or more periods of time. In one example, the command rate can be set to a fastest level. In another example, the command rate can be incrementally increased over periods of time. If a request to lower the command rate is received, the command rate can be set to a reference level or can be decremented to one slower rate level. In one or more embodiments, the one or more requests to lower the command rate can be based on at least one of an issue rate of speculative commands and a number of overcommit failures, among others.