Abstract: A method, apparatus and computer program product are provided for detecting and powering off unused I/O slots in a computer system. For each of the I/O slots, the current slot is checked to determine if the slot is powered on and unlocked. When the current slot is powered on and unlocked, the current slot is checked to determine if the current slot is a candidate for being powered off. When the current slot is determined to be a candidate for being powered off, then the current slot is powered off and the checking continues with a next one of the I/O slots. Recording the slot as a candidate for being powered off before the slot is actually powered off ensures a proper delay to avoid powering off a slot that is about to be locked, which could cause slot power cycles in quick succession.

Abstract: A one writer, multiple readers, shared data table concurrent access process includes providing a plurality of data elements. The data elements include a serialization mechanism. A second data element is a table/array of elements. A third data element is an atomic, integer counter. Inserting a new element into the shared unsorted data table by a writer includes locking the table. Removing an element at a position in the shared unsorted data table by a writer includes locking the table, copying the table so that the element to be removed is at the end of the table, deleting the element at the end of the table, and unlocking the table. From the shared data table by a reader includes looping through all elements of the table, loading and caching each element of the table, and read-only processing each element of the table.

Abstract: A logical partition debugger allows debugging one logical partition in a computer system without requiring the shutdown of other logical partitions. The logical partition debugger is implemented in software in the partition manager. The logical partition debugger provides many common debug functions known in existing hardware and software debuggers, but does so in a manner that only the partition being debugged is affected.

Abstract: A method, apparatus and computer program product are provided for detecting and powering off unused I/O slots in a computer system. For each of the I/O slots, the current slot is checked to determine if the slot is powered on and unlocked. When the current slot is powered on and unlocked, the current slot is checked to determine if the current slot is a candidate for being powered off. When the current slot is determined to be a candidate for being powered off, then the current slot is powered off and the checking continues with a next one of the I/O slots. Recording the slot as a candidate for being powered off before the slot is actually powered off ensures a proper delay to avoid powering off a slot that is about to be locked, which could cause slot power cycles in quick succession.

Abstract: An apparatus, program product and method to manage access to a shared resource by a plurality of processes in a multithreaded computer via a collection of atomic operations that track both the order in which requests that use a shared resource are received, and the order in which processing of such requests are completed after they are received. Dispatching of requests is effectively deferred until processing of all non-dispatched requests that were received earlier than a most recently completed request has been completed. In many instances, completion of processing of requests can be performed non-atomically, thus reducing contention issues with respect to the shared resource. Furthermore, dispatching of requests may be batched to reduce the overhead associated with individual dispatch operations.

Abstract: A resource and partition manager includes a power on/power off mechanism that is used to assure a hardware resource is powered down when control of the resource is removed from a logical partition, and to assure the hardware resource is powered up when control of the hardware resource is transferred to a logical partition. In the alternative, the resource and partition manager may simply place the hardware resource in a power on reset state when the hardware resource is transferred to a logical partition. In this manner, when made available to a partition, the hardware resource is in a power-on reset state, which is the state typically expected by the logical partition.

Abstract: A resource and partition manager of the preferred embodiments includes a lock mechanism that operates on a plurality of locks that control access to individual hardware resources. The resource and partition manager uses the lock mechanism to obtain a lock on a hardware resource when transferring control of the hardware resource to a logical partition that is powering on and when removing the hardware resource from a logical partition that is powering off. The resource and partition manager uses the lock mechanism to remove control of a hardware resource from, or return control to, an operating logical partition in order to facilitate hardware service operations on that hardware resource or on the physical enclosure in which it is contained.

Abstract: A method for dispatching input/output access requests to a direct access storage device (DASD) is disclosed. Each of a group of I/O access requests to DASD is assigned into one of at least two I/O access request categories, namely, high priority I/O access requests and low priority I/O access requests. Each of a group of I/O slots within DASD is assigned into one of at least two I/O slot categories, namely, high priority I/O slots and low priority I/O slots. An I/O access request from a first one of the two I/O access request categories is sent to any one of the I/O slots. An I/O access request from a second one of the two I/O access request categories is sent to only a slot belonging to a subset of the two I/O slot categories.

Abstract: An apparatus and method for monitoring the state of a computer system running multiple operating systems shared by a partition manager is provided. A dedicated service processor monitors the individual run state condition of a plurality of processors running a plurality of operating systems. The service processor executes a routine to poll a memory location in each processor in the system to determine if the processor has entered an error loop with interrupts disabled. If any one of the plurality of processors are in an error loop, the service processor executes a routine to send a non-maskable interrupt to the looped processor so that the partition manager may regain control of the processor.

Abstract: A partition manager for managing logical partitions in a computer system includes hooks to low-level operating system code in one of the logical partitions. By using the operating system code to manage the resources of a computer system, any changes that are made to the operating system are automatically reflected in the function of the partition manager. In addition, low-level functions of operating systems, which are often well-debugged and tested, can be used when generating a new partition manager, greatly simplifying the time and reducing the cost of producing a partition manager.

Abstract: A method for dispatching input/output access requests to a direct access storage device (DASD) is disclosed. Each of a group of I/O access requests to DASD is assigned into one of at least two I/O access request categories, namely, high priority I/O access requests and low priority I/O access requests. Each of a group of I/O slots within DASD is assigned into one of at least two I/O slot categories, namely, high priority I/O slots and low priority I/O slots. An I/O access request from a first one of the two I/O access request categories is sent to any one of the I/O slots. An I/O access request from a second one of the two I/O access request categories is sent to only a slot belonging to a subset of the two I/O slot categories.

Abstract: An apparatus and method for monitoring the state of a computer system running multiple operating systems shared by a partition manager is provided. A dedicated service processor monitors the individual run state condition of a plurality of processors running a plurality of operating systems. The service processor executes a routine to poll a memory location in each processor in the system to determine if the processor has entered an error loop with interrupts disabled. If any one of the plurality of processors are in an error loop, the service processor executes a routine to send a non-maskable interrupt to the looped processor so that the partition manager may regain control of the processor.

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 one writer, multiple readers, shared data table concurrent access process includes providing a plurality of data elements. The data elements include a serialization mechanism, where at most one writer is able to modify shared data, and readers do not use this serialization at all. A second data element is a table/array of elements, wherein each element of the table must be able to be updated atomically by a processor with a load or store instruction. A third data element is an atomic, integer counter that indicates how many shared data elements are contained in the table. Inserting a new element into the shared unsorted data table by a writer includes locking the table, wherein other writers are prevented from writing to the table, putting the new element at the end of the table, making the new element visible to all readers, and unlocking the table.