Abstract: A method, computer program product and system for switching a defective signal line with a spare signal line without shutting down the computer system. A service processor monitors error correction code (ECC) check units configured to detect an error in a signal line. If an ECC check unit detects an error rate that exceeds a threshold, then the signal line with such an error rate may be said to be “defective.” The service processor configures switch control units in the driver/receiver pair associated with the defective signal line to be able to switch the defective signal line with a spare line upon receipt of a command from a memory controller switch control unit. In this manner, the system is not deactivated in order to switch a defective signal line with a spare line thereby reducing the time that the processor cannot send information to the memory buffers.

Abstract: A method and apparatus for invalidating cache lines during direct memory access (DMA) write operations are disclosed. Initially, a multi-cache line DMA request is issued by a peripheral device. The multi-cache line DMA request is snooped by a cache memory. A determination is then made as to whether or not the cache memory includes a copy of data stored in the system memory locations to which the multi-cache line DMA request are directed. In response to a determination that the cache memory includes a copy of data stored in the system memory locations to which the multi-cache line DMA request are directed, multiple cache lines within the cache memory are consecutively invalidated.

Abstract: A data processing system includes a plurality of communication links and a plurality of processing units including a local master processing unit. The local master processing unit includes interconnect logic that couples the processing unit to one or more of the plurality of communication links and an originating master coupled to the interconnect logic. The originating master originates an operation by issuing a write-type request on at least one of the one or more communication links, receives from a snooper in the data processing system a destination tag identifying a route to the snooper, and, responsive to receipt of the combined response and the destination tag, initiates a data transfer including a data payload and a data tag identifying the route provided within the destination tag.

Abstract: A cache coherent data processing system includes at least first and second coherency domains each including at least one processing unit. The first coherency domain includes a first cache memory, and the second coherency domain includes a coherent second cache memory. The first cache memory within the first coherency domain of the data processing system holds a memory block in a storage location associated with an address tag and a coherency state field. The coherency state field is set to a state that indicates that the address tag is valid, that the storage location does not contain valid data, and that the memory block is likely cached only within the first coherency domain.

Abstract: In a data processing system, a plurality of agents communicate operations therebetween. Each operation includes a request and a combined response representing a system-wide response to the request. Within data storage in the data processing system, a data structure indicates a duration of a protection window extension for each of the plurality of agents. Each protection window extension is a period following receipt of a combined response during which an associated one of the plurality of agents protects transfer of coherency ownership of a data granule between agents. Each of the plurality of agents is configured with a duration of a protection window extension by reference to the data structure, and at least two of the agents have protection window extensions of differing durations. The plurality of agents thereafter employ the configured protection window extensions.

Abstract: A data processing system includes at least a first processing node having an input/output (I/O) controller and a second processing including a memory controller for a memory. The memory controller receives, in order, pipelined first and second DMA write operations from the I/O controller, where the first and second DMA write operations target first and second addresses, respectively. In response to the second DMA write operation, the memory controller establishes a state of a domain indicator associated with the second address to indicate an operation scope including the first processing node. In response to the memory controller receiving a data access request specifying the second address and having a scope excluding the first processing node, the memory controller forces the data access request to be reissued with a scope including the first processing node based upon the state of the domain indicator associated with the second address.

Abstract: According to one embodiment, a method of coherency management in a data processing system includes holding a cache line in an upper level cache memory in an exclusive ownership coherency state and thereafter removing the cache line from the upper level cache memory and transmitting a castout request for the cache line from the upper level cache memory to a lower level cache memory. The castout request includes an indication of a shared ownership coherency state. In response to the castout request, the cache line is placed in the lower level cache memory in a coherency state determined in accordance with the castout request.

Abstract: A cache coherent data processing system includes at least first and second coherency domains. The first coherency domain includes a system memory controller for a system memory and a first processing unit having a first cache memory. The second coherency domain includes a second processing unit having a second cache memory. In the first cache memory, a coherency state field associated with a storage location and an address tag is set to a first coherency state. In response to snooping an exclusive access request specifying a target address matching the address tag, the first cache memory provides a first partial response to the exclusive access request based at least in part upon the first coherency state. In response to snooping the exclusive access request, the memory controller determines whether it is responsible for the target address and provides a second partial response to the exclusive access request based at least in part upon an outcome of the determination.

Abstract: A method of interfacing two components of a computing system is provided wherein the method includes providing a pair of unidirectional, point-to-point buses to transmit data between a master bus controller of the computing system and a slave bus controller of a processor unit of the computing system. The method also includes providing means for transmitting a command packet with an address associated with data pertaining to the command from the master bus controller to the slave bus controller. In addition, the method includes providing means for determining by the slave bus controller whether the slave bus controller can accept the command. The method further includes providing means for transmitting an acknowledgement from the slave bus controller to the master bus controller after the slave bus controller receives a first signaling interval for the command packet if the slave bus controller can accept the command packet.

Abstract: A method of interfacing two components of a computing system is provided wherein the method includes providing a pair of unidirectional, point-to-point buses to transmit data between a master bus controller of the computing system and a slave bus controller of a processor unit of the computing system. The method also includes providing means for transmitting a command packet with an address associated with data pertaining to the command from the master bus controller to the slave bus controller. In addition, the method includes providing means for determining by the slave bus controller whether the slave bus controller can accept the command. The method further includes providing means for transmitting an acknowledgement from the slave bus controller to the master bus controller after the slave bus controller receives a first signaling interval for the command packet if the slave bus controller can accept the command packet.

Abstract: A data processing system, method, and computer-usable medium for recovering from a hang condition in a data processing system. The data processing system includes a collection of coupled processing units. The processing units include a collection of processing unit components such as, two or more processing cores, and a cache array, a processor core master, a cache snooper, and a local hang manager. The local hang manager determines whether at least one component out of the collection of processing unit components has entered into a hang condition. If the local hang manager determines at least one component has entered into a hang condition, a throttling manager throttles the performance of the processing unit in an attempt to break the at least one component out of the hang condition.

Abstract: A data processing system includes a plurality of processing units coupled for communication by a communication link and a configuration register. The configuration register has a plurality of different settings each corresponding to a respective one of a plurality of different link information allocations. Information is communicated over the communication link in accordance with a particular link information allocation among the plurality of link information allocations determined by a respective setting of the configuration register.

Abstract: A data processing system, method, and computer-usable medium for recovering from a hang condition in a data processing system. The data processing system includes a collection of coupled processing units. The processing units include a collection of processing unit components such as, two or more processing cores, and a cache array, a processor core master, a cache snooper, and a local hang manager. The local hang manager determines whether at least one component out of the collection of processing unit components has entered into a hang condition. If the local hang manager determines at least one component has entered into a hang condition, a throttling manager throttles the performance of the processing unit in an attempt to break the at least one component out of the hang condition.

Abstract: Scrubbing logic in a local coherency domain issues a domain query request to at least one cache hierarchy in a remote coherency domain. The domain query request is a non-destructive probe of a coherency state associated with a target memory block by the at least one cache hierarchy. A coherency response to the domain query request is received. In response to the coherency response indicating that the target memory block is not cached in the remote coherency domain, a domain indication in the local coherency domain is updated to indicate that the target memory block is cached, if at all, only within the local coherency domain.

Abstract: Scrubbing logic in a local coherency domain issues to at least one cache hierarchy in a remote coherency domain a domain reset request that forces invalidation of any cached copy of a target memory block then held in said remote coherency domain. A coherency response to said domain reset request is received. In response to said coherency response indicating that said target memory block is not cached in said remote coherency domain, a domain indication of said local coherency domain is updated to indicate that said target memory block is cached, if at all, only within said local coherency domain.

Abstract: In response to execution of program code, a control register within scrubbing logic in a local coherency domain is initialized with at least a target address of a target memory block. In response to the initialization, the scrubbing logic issues to at least one cache hierarchy in a remote coherency domain a domain indication scrubbing request targeting a target memory block that may be cached by the at least one cache hierarchy. In response to receipt of a coherency response indicating that the target memory block is not cached in the remote coherency domain, a domain indication in the local coherency domain is updated to indicate that the target memory block is cached, if at all, only within the local coherency domain.

Abstract: A method and apparatus for invalidating cache lines during direct memory access (DMA) write operations are disclosed. Initially, a multi-cache line DMA request is issued by a peripheral device. The multi-cache line DMA request is snooped by a cache memory. A determination is then made as to whether or not the cache memory includes a copy of data stored in the system memory locations to which the multi-cache line DMA request are directed. In response to a determination that the cache memory includes a copy of data stored in the system memory locations to which the multi-cache line DMA request are directed, multiple cache lines within the cache memory are consecutively invalidated.

Abstract: A cache coherent data processing system includes a memory and at least first and second coherency domains that each include a respective one of first and second cache memories. A master in the first coherency domain selects a scope of an initial broadcast of an operation targeting a request address allocated to the memory from among a first scope including only the first coherency domain and a second scope including both the first and second coherency domains. The master selects the scope based, at least in part, upon whether the memory belongs to the first coherency domain and performs an initial broadcast of the operation within the cache coherent data processing system utilizing the selected scope.

Abstract: A method and apparatus for invalidating cache lines during direct memory access (DMA) write operations are disclosed. Initially, a multi-cache line DMA request is issued by a peripheral device. The multi-cache line DMA request is snooped by a cache memory. A determination is then made as to whether or not the cache memory includes a copy of data stored in the system memory locations to which the multi-cache line DMA request are directed. In response to a determination that the cache memory includes a copy of data stored in the system memory locations to which the multi-cache line DMA request are directed, multiple cache lines within the cache memory are consecutively invalidated.

Abstract: A data processing system includes a plurality of processing units coupled by a plurality of communication links for point-to-point communication such that at least some of the communication between multiple different ones of the processing units is transmitted via intermediate processing units among the plurality of processing units. The communication includes operations having a request and a combined response representing a system response to the request.