Abstract: A uniform application programming interface (API) provides efficient generation and control of resource reservations so as to ensure a desired quality of service (QoS) for applications running on an operating system of a computer system. The uniform API is based on a hierarchical file system which associates resource reservations with references to shared objects, rather than with the objects themselves. The uniform API permits the use of a variety of different proportional share schedulers for controlling access to physical resources, e.g., CPU, memory, disk, network interfaces, etc. of the computer system. The hierarchical file system includes a separate directory for each independently-scheduled physical resource of the computer system. A parent of the resource reservation in the hierarchical file system is either a root node of the file system or another reservation for the same resource.

Abstract: A computer operating system that allows legacy applications to be run automatically with quality of service (QoS) guarantees matching required QoS performance levels. In accordance with the invention, files have QoS requirement attributes that can be set-by users. Additionally, users may interpose a requirement broker between a given legacy application and the operating system. The requirement broker may be in the form of a modified version of a library that is dynamically linked with applications at load time. The requirement broker intercepts certain system calls and automatically requests from the system QoS guarantees in accordance with the QoS requirement attributes of the accessed files, whether local or remote.

Abstract: A computer operating system in which transfer of control of executing threads between protection domains is implemented using specific portals dedicated to the particular transfer of control between two protection domains. The transfer of control may also include parameter manipulation. A server registers a portal specification with a portal manager, the portal specification defining the behavior of portals which transfer control to the server. Thereafter, when a client application desires service from the server, the client application requests instantiation of a portal which will transfer control of an execution thread from the client application protection domain to the server protection domain. Upon receipt of the request, the portal manager dynamically generates portal code and updates a portal table associated with the client application, thus instantiating the portal.

Abstract: A method and system for servicing disk I/O requests from domains which have been guaranteed minimum quality of disk service maintains I/O requests for each domain are in separate queues. The queues are serviced by a disk scheduler which selects requests from the queues in accordance with a fair queuing scheduling algorithm that considers the estimated time required to service the request at the head of a queue with regard for the size of the input or output associated with the request, the proportion of disk bandwidth assigned to the particular domain, and the state of the other queues.

Abstract: A new scheduling method and policy for shared (server) resources, such as the CPU or disk memory of a multiprogrammed data processor. The scheduling is referred to as Move-To-Rear List Scheduling and it provides a cumulative service guarantee and well as more traditional guarantees such as fairness (proportional sharing) and bounded delay. In typical operation, a list is maintained for a server of processes seeking service from the server. Processes are admitted to the list only when maximum capacity constraints are not violated, and once on the list, are served in a front-to-back order. After receiving service, or upon the occurrence of other events, the position of the process on the list may be changed.