Abstract: In a multinode data processing system in which the nodes communicate with one another via communication adapters over a network or switch, the adapters are provided with a dual register mechanism for tracking microcode task status. Upon the issuance of a disruptive command that requires attention from one of the nodes, the task status maintained in one register is copied to the snapshot register. As tasks within the adapter are completed, both registers are updated, thus providing a mechanism for the nodes to determine that all tasks active at the time of the disruptive command have completed. This means that the nodes now have a mechanism for determining, as soon as possible, that all tasks that are active when a disruptive command occurs have completed, thus allowing the data processing node to perform such operations as releasing system memory that is associated with the disruptive command, thus eliminating temporal overhead that can affect performance.

Abstract: In remote direct memory access (RDMA) transfers in a multinode data processing system in which the nodes communicate with one another through communication adapters coupled to a switch or network, there is a need for the system to ensure efficient memory protection mechanisms across jobs. A method is thus desired for addressing virtual memory on local and remote servers that is independent of the process ID on the local and/or remote node. The use of global Translation Control Entry (TCE) tables that are accessed/owned by RDMA jobs and are managed by a device driver in conjunction with a Protocol Virtual Offset (PVO) address format solves this problem.

Abstract: In a multinode data processing system in which data is transferred, via direct memory access (DMA) or in remote direct memory access (RDMA), from a source node to at least one destination node through communication adapters coupling each node to a network or switch, a method is provided in which interrupt handling is overlapped with data transfer so as to allow interrupt processing overhead to run in parallel at the destination node with the movement of data to provide performance benefits. The method is also applicable to situations involving multiple interrupt levels corresponding to multithreaded handling capabilities.

Abstract: In remote direct memory access transfers in a multinode data processing system in which the nodes communicate with one another through communication adapters coupled to a switch or network, failures in the nodes or in the communication adapters can produce the phenomenon known as trickle traffic, which is data that has been received from the switch or from the network that is stale but which may have all the signatures of a valid packet data. The present invention addresses the trickle traffic problem in two situations: node failure and adapter failure. In the node failure situation randomly generated keys are used to reestablish connections to the adapter while providing a mechanism for the recognition of stale packets. In the adapter failure situation, a round robin context allocation approach is used with adapter state contexts being provided with state information which helps to identify stale packets.

Abstract: In a multinode data processing system in which nodes exchange information over a network or through a switch, a structure and mechanism is provided within the realm of Remote Direct Memory Access (RDMA) operations in which DMA operations are present on one side of the transfer but not the other. On the side in which the transfer is not carried out in DMA fashion, transfer processing is carried out under program control; this is in contrast to the transfer on the DMA side which is characteristically carried out in hardware. Usage of these combination processes is useful in programming situations where RDMA is carried out to or from contiguous locations in memory on one side and where memory locations on the other side is noncontiguous. This split mode of transfer is provided both for read and for write operations.

Abstract: A system and method that utilizes a dedicated transmission queue to enable expedited transmission of data messages to adaptive “nearest neighbor” nodes within a cluster. Packet descriptors are pre-fetched by the communications adapter hardware during the transmission of the preceding data element and setup for the next transmission is performed in parallel with the transmission of the preceding data element. Data elements of a fixed length that is equal to the cache line size of the communication hardware can optionally be used to provide optimized transfer between computer memory and communications hardware. The data receiving processing can also be optimized to recognize and handle cache line size data elements.