Abstract: Embodiments relate to accessing a cache line on a multi-level cache system having a system memory. Based on a request for exclusive ownership of a specific cache line at the local node, requests are concurrently sent to the system memory and remote nodes of the plurality of nodes for the specific cache line by the local node. The specific cache line is found in a specific remote node. The specific remote node is one of the remote nodes. The specific cache line is removed from the specific remote node for exclusive ownership by another node. Based on the specified node having the specified cache line in ghost state, any subsequent fetch request is initiated for the specific cache line from the specific node encounters the ghost state. When the ghost state is encountered, the subsequent fetch request is directed only to nodes of the plurality of nodes.

Abstract: An apparatus for controlling access to a pipeline includes a plurality of command queues including a first subset of the plurality of command queues being assigned processes the commands of first command type, a second subset of the plurality of command queues being assigned to process commands of the second command type, and a third subset of the plurality of the command queues not being assigned to either the first subset or the second subset. The apparatus also includes an input controller configured to receive requests having the first command type and the second command type and assign requests having the first command type to command queues in the first subset until all command queues in the first subset are filled and then assign requests having the first command type to command queues in the third subset.

Abstract: A method and apparatus for eliminating, in a multi-nodes data handling system, contention for exclusivity of lines in cache memory through improved management of system buses, processor cross-invalidate stacks, and the system operations that can lead to these requested cache operations being rejected.

Abstract: A mechanism for controlling data stream interruptions on a shared bus is provided. A first request is received to transfer data. High priority data components and low priority data components are determined for the first request. The high priority data components are transferred without interruptions. In response to receiving requests when transferring the high priority data components, the received requests are rejected.

Abstract: Various embodiments of the present invention manage access to a cache memory. In one embodiment, a set of cache bank availability vectors are generated based on a current set of cache access requests currently operating on a set of cache banks and at least a variable busy time of a cache memory includes the set of cache banks. The set of cache bank availability vectors indicate an availability of the set of cache banks. A set of cache access requests for accessing a set of given cache banks within the set of cache banks is received. At least one cache access request in the set of cache access requests is selected to access a given cache bank based on the a cache bank availability vectors associated with the given cache bank and the set of access request parameters associated with the at least one cache access that has been selected.

Abstract: Maintaining cache coherence in a multi-node, symmetric multiprocessing computer, the computer composed of a plurality of compute nodes, including, broadcasting upon a cache miss by a first compute node a request for a cache line; transmitting from each of the other compute nodes to all other nodes the state of the cache line on that node, including transmitting from any compute node having a correct copy to the first node the correct copy of the cache line; and updating by each node the state of the cache line in each node, in dependence upon one or more of the states of the cache line in all the nodes.

Abstract: Managing concurrent serialized interrupt broadcast commands in a multi-node, symmetric multiprocessing computer including receiving, by a communications adapter in a compute node, a plurality of serialized interrupt broadcast commands; receiving, by the communications adapter, a plurality of interrupt tags for the plurality of serialized interrupt broadcast commands, each interrupt tag including an identification of an interrupt service order for a serialized interrupt broadcast command; assigning, by the communications adapter, to each serialized interrupt broadcast command its interrupt tag; and if an interrupt tag assigned to a serialized interrupt broadcast command has an interrupt service order that matches a value of a current operation tag that identifies the next serialized interrupt broadcast command to be exposed to the one or more processors, exposing, by the communications adapter, the serialized interrupt broadcast command to the one or more processors on the compute node to be serviced.

Abstract: Horizontal cache persistence in a multi-compute node, SMP computer, including, responsive to a determination to evict a cache line on a first one of the compute nodes, broadcasting by a first compute node an eviction notice for the cache line; transmitting the state of the cache line receiving compute nodes, including, if the cache line is missing from a compute node, an indication whether that compute node has cache storage space available for the cache line; determining by the first compute node, according to the states of the cache line and space available, whether the first compute node can evict the cache line without writing the cache line to main memory; and updating by each compute node the state of the cache line in each compute node, in dependence upon one or more of the states of the cache line in all the compute nodes.

Abstract: Serializing instructions in a multiprocessor system includes receiving a plurality of processor requests at a central point in the multiprocessor system. Each of the plurality of processor requests includes a needs register having a requestor needs switch and a resource needs switch. The method also includes establishing a tail switch indicating the presence of the plurality of processor requests at the central point, establishing a sequential order of the plurality of processor requests, and processing the plurality of processor requests at the central point in the sequential order.

Abstract: Various embodiments of the present invention manage access to a cache memory. In one embodiment, a set of cache bank availability vectors are generated based on a current set of cache access requests currently operating on a set of cache banks and at least a variable busy time of a cache memory includes the set of cache banks. The set of cache bank availability vectors indicate an availability of the set of cache banks. A set of cache access requests for accessing a set of given cache banks within the set of cache banks is received. At least one cache access request in the set of cache access requests is selected to access a given cache bank based on the a cache bank availability vectors associated with the given cache bank and the set of access request parameters associated with the at least one cache access that has been selected.

Abstract: A mechanism for controlling data stream interruptions on a shared bus is provided. A first request is received to transfer data. High priority data components and low priority data components are determined for the first request. The high priority data components are transferred without interruptions. In response to receiving requests when transferring the high priority data components, the received requests are rejected.

Abstract: An apparatus for controlling access to a pipeline includes a plurality of command queues including a first subset of the plurality of command queues being assigned processes the commands of first command type, a second subset of the plurality of command queues being assigned to process commands of the second command type, and a third subset of the plurality of the command queues not being assigned to either the first subset or the second subset. The apparatus also includes an input controller configured to receive requests having the first command type and the second command type and assign requests having the first command type to command queues in the first subset until all command queues in the first subset are filled and then assign requests having the first command type to command queues in the third subset.

Abstract: Managing concurrent serialized interrupt broadcast commands in a multi-node, symmetric multiprocessing computer including receiving, by a communications adapter in a compute node, a plurality of serialized interrupt broadcast commands; receiving, by the communications adapter, a plurality of interrupt tags for the plurality of serialized interrupt broadcast commands, each interrupt tag including an identification of an interrupt service order for a serialized interrupt broadcast command; assigning, by the communications adapter, to each serialized interrupt broadcast command its interrupt tag; and if an interrupt tag assigned to a serialized interrupt broadcast command has an interrupt service order that matches a value of a current operation tag that identifies the next serialized interrupt broadcast command to be exposed to the one or more processors, exposing, by the communications adapter, the serialized interrupt broadcast command to the one or more processors on the compute node to be serviced.

Abstract: Maintaining cache coherence in a multi-node, symmetric multiprocessing computer, the computer composed of a plurality of compute nodes, including, broadcasting upon a cache miss by the first compute node to other compute nodes a request for the cache line; if at least two of the compute nodes has a correct copy of the cache line, selecting which compute node is to transmit the correct copy of the cache line to the first node, and transmitting from the selected compute node to the first node the correct copy of the cache line; and updating by each node the state of the cache line in each node, in dependence upon one or more of the states of the cache line in all the nodes.

Abstract: Main memory operation in a symmetric multiprocessing computer, the computer comprising one or more processors operatively coupled through a cache controller to at least one cache of main memory, the main memory shared among the processors, the computer further comprising input/output (‘I/O’) resources, including receiving, in the cache controller from an issuing resource, a memory instruction for a memory address, the memory instruction requiring writing data to main memory; locking by the cache controller the memory address against further memory operations for the memory address; advising the issuing resource of completion of the memory instruction before the memory instruction completes in main memory; issuing by the cache controller the memory instruction to main memory; and unlocking the memory address only after completion of the memory instruction in main memory.

Abstract: Horizontal cache persistence in a multi-compute node, SMP computer, including, responsive to a determination to evict a cache line on a first one of the compute nodes, broadcasting by a first compute node an eviction notice for the cache line; transmitting the state of the cache line receiving compute nodes, including, if the cache line is missing from a compute node, an indication whether that compute node has cache storage space available for the cache line; determining by the first compute node, according to the states of the cache line and space available, whether the first compute node can evict the cache line without writing the cache line to main memory; and updating by each compute node the state of the cache line in each compute node, in dependence upon one or more of the states of the cache line in all the compute nodes.

Abstract: Maintaining cache coherence in a multi-node, symmetric multiprocessing computer, the computer composed of a plurality of compute nodes, including, broadcasting upon a cache miss by a first compute node a request for a cache line; transmitting from each of the other compute nodes to all other nodes the state of the cache line on that node, including transmitting from any compute node having a correct copy to the first node the correct copy of the cache line; and updating by each node the state of the cache line in each node, in dependence upon one or more of the states of the cache line in all the nodes.

Abstract: A storage system may include storage, a main pipeline to carry data for the storage, and a store pipeline to carry data for the storage. The storage system may also include a controller to prioritize data storage requests for the storage based upon available interleaves and which pipeline is associated with the data storage requests.

Abstract: A method for pipeline arbitration including receiving a first request for a shared chip interface from a first pipeline, determining whether a response bus of the shared chip interface is needed by the first request, and if it is determined that the response bus is not needed by the first request, concluding that the first request needs just an address bus of the shared chip interface, arbitrating the first request with a second request for the shared chip interface received from a second pipeline for access to the address bus, sending the first request to the address bus if the first request wins the arbitration over the second request, and rejecting the first request if the second request wins the arbitration over the first request. A corresponding system and computer program product.

Abstract: A method for pipeline arbitration including receiving a first request for a shared chip interface from a first pipeline, determining whether a response bus of the shared chip interface is needed by the first request, and if it is determined that the response bus is not needed by the first request, concluding that the first request needs just an address bus of the shared chip interface, arbitrating the first request with a second request for the shared chip interface received from a second pipeline for access to the address bus, sending the first request to the address bus if the first request wins the arbitration over the second request, and rejecting the first request if the second request wins the arbitration over the first request. A corresponding system and computer program product.