Abstract: A method and apparatus for managing contention among users for access to resources in a multisystem cluster by identifying contention chains in which each user is waiting for a resource held by the user(s) before it in the chain and allocating system resources to the user(s) at the head of the chain as if their need were at least that of the neediest waiter in the chain. The contention data necessary for optimal resource allocation is effectively distributed across the system cluster, even though the data flow between systems is minimal and no system has a complete view of cross-system contention. Each system tracks resources in contention having local users as either holders or waiters and groups such resources into clusters of resources involved in contention chains in which each resource is either held by a local user waiting for another resource in the cluster or being waited for by a local user holding another resource in the cluster.

Abstract: A method and apparatus for managing contention among users for access to resources in a multisystem cluster by identifying contention chains in which each user is waiting for a resource held by the user(s) before it in the chain and allocating system resources to the user(s) at the head of the chain as if their need were at least that of the neediest waiter in the chain. The contention data necessary for optimal resource allocation is effectively distributed across the system cluster, even though the data flow between systems is minimal and no system has a complete view of cross-system contention. Each system tracks resources in contention having local users as either holders or waiters and groups such resources into clusters of resources involved in contention chains in which each resource is either held by a local user waiting for another resource in the cluster or being waited for by a local user holding another resource in the cluster.

Abstract: A method and apparatus to determine the piece-wise homogeneity of data, i.e., whether the data of a set Ry consists entirely of data from a single set Sz over a period of time. In operation, for each set of data in a service class Sz, the identity of the last source and a unique “signature” which changes each time the source changes is recorded. This information is provided along with the existing data to the data consumers. Each data consumer can then determine homogeneity by comparing the ending signature with the starting signature for any interval. If the data is homogeneous, the signature is the same, and subdivisions applicable to set Sz are applicable to Ry. In another embodiment, a data provider makes observations at regularly scheduled intervals, in an interval mode of operation rather than providing data in total mode.

Abstract: A method and apparatus for controlling the number of servers in a multisystem cluster. Incoming work requests are organized into service classes, each of which has a queue serviced by servers across the cluster. Each service class has defined for it a local performance index for each particular system of the cluster and a multisystem performance index for the cluster as a whole. Each system selects one service class as a donor class for donating system resources and another service class as a receiver class for receiving system resources, based upon how well the service classes are meeting their goals. Each system then determines the resource bottleneck causing the receiver class to miss its goals.

Abstract: A method and apparatus for controlling the number of servers in an information handling system in which incoming work requests belonging to a first service class are placed in a queue for processing by one or more servers. The system also has units of work assigned to a second service class that acts as a donor of system resources. In accordance with the invention, a performance measure is defined for the first service class as well as for the second service class. Before adding servers to the first service class, there is determined not only the positive effect on the performance measure for the first service class, but also the negative effect on the performance measure for the second service class. Servers are added to the first service class only if the positive effect on the performance measure for the first service class outweighs the negative effect on the performance measure for the second service class.