Abstract: An apparatus, program product, and method utilize a memory access interrupt to effect a reset of a processor in a multi-processor environment. Specifically, a source processor is permitted to initiate a reset of a target processor simply by generating both a reset request and a memory access interrupt for the target processor. The target processor is then specifically configured to detect the presence of a pending reset request during handing of the memory access interrupt, such that the target processor will perform a reset operation responsive to detection of such a request.

Abstract: A method of handling conflicts between threads, including an initiating thread and at least one other thread, for at least one shared resource in a multi-threaded processing system having a processor and memory includes setting a location in memory for each other thread on the processor with the initiating thread. The initiating thread signals an inter-processor interrupt (IPI) to all other threads on the processor. For each other thread, an interrupt handler is initiated where each other thread: acknowledges receipt of the interrupt, and proceeds to spin on the respective location in memory that was set, thereby guaranteeing that the respective other thread will not be using any shared resource of the processor.

Abstract: A journal mechanism for a database allows simultaneous deposits on multiple journal arms. According to a first embodiment, a journaling system maintains the time-order of interdependent deposits on the journal, but does not necessarily maintain the time-order of deposits that are independent of each other, thereby providing multiple simultaneous deposit points on the journal. The first embodiment provides excellent scaling of journal functions as processors are added to a database computer system. According to a second embodiment, a journaling system maintains the time-order of deposits on the journal, but allows a group of deposits known as a “bundle” to span multiple journal arms, thereby providing multiple simultaneous deposit points on the journal. The second embodiment provides good scaling while providing compatibility with known database systems. The present invention thus relieves contention for the journal that exists as the number of processors increases in a database system.

Abstract: An apparatus, program product and method utilize an event-driven communications interface to support communications between multiple logical partitions in a logically-partitioned computer. The event-driven communications interface is at least partially disposed within a partition manager that is accessible to each of the logical partitions. Events are typically passed between logical partitions in the form of messages that are passed first from a source logical partition that initiates the event, through the partition manager, and then to a target logical partition to which the event is directed, while maintaining the independent address spaces associated with the logical partitions.

Abstract: An interrupt and message batching apparatus and method reduces the number and frequency of processor interrupts and resulting context switches by grouping I/O completion events together with a single processor interrupt in a manner that balances I/O operation latency requirements with processor utilization requirements to optimize overall computer system performance. The invention sends a message from a processor complex to an I/O adapter on an I/O bus commanding an I/O device connected to the I/O adapter to perform a function. Upon completion of the commanded function, the message processor in the I/O adapter generates a message and sends it to the processor complex on the I/O bus. The message is enqueued in the message queue of the memory, a message count is updated, and processor complex interrupt is signalled if and when the message count exceeds a message pacing count.

Abstract: A method for processing timer requests efficiently by reducing overhead and by increasing scalability within a computer system is disclosed. A timer request having a wake-up time of moderate length and a high tolerance level such that the wake-up time does not have to be very precise, is placed in a drop-off queue which is made up of an unsorted double-linked list. The timer request is then periodically hashed from the drop-off queue into an appropriate element of a timer request array, according to the time duration of the timer request. The timer request array is then processed in order to migrate the timer request towards the ?0,0! element of the timer request array. Finally, the timer request is awakened when the time request reaches the ?0,0! element or a ?0,n! element of the timer request array with no time remaining.