Abstract: A system and method for maintaining consistency in a system where multiple copies of an object may exist is provided for maintaining consistent copies. Consistency is maintained using a plurality of consistency policies in which at least one consistency policy results in different performance than a second consistency policy. A consistency policy is selected from the plurality consistency policies for each object to improve system performance.

Abstract: The present invention concerns methods and apparatus for implementing a multi-user advance reservation system where reservations are specified in terms of flexible constraints, inflexible constraints and business values. The specification of reservations in this manner allows an entity managing the reservation system to arbitrate among reservations received from a user population with a view toward maximizing business value across the user population. In methods and apparatus of the present invention, penalties and rewards associated with various reservation outcomes can be specified in reservations to assist in business value maximization. In an example, a reservation having a low business value may be declined when there is a significant possibility that a reservation having a high business would be submitted during the pendency of service delivery to the user issuing the reservation with a low business value.

Abstract: A system and method for disseminating policies to multiple policy-based components includes a policy producer which generates a group of policies to be enforced. A policy disseminator classifies each policy with a type, and for each policy type, the policy disseminator identifies policy-based components that handle a corresponding policy type. The policy disseminator sends specific policy types from the group of policies to each policy-based component that can handle that specific policy type.

Abstract: A system and method for maintaining consistency in a system where multiple copies of an object may exist is provided for maintaining consistent copies. Consistency is maintained using a plurality of consistency policies in which at least one consistency policy results in different performance than a second consistency policy. A consistency policy is selected from the plurality consistency policies for each object to improve system performance.

Abstract: In a system having a plurality of caches, a method for maintaining cached objects includes storing an object in a plurality of caches. In response to a request to update the object, a future invalidation time is determined when the object should be invalidated in caches currently storing the object. Updating of the object is delayed until the invalidation time has passed.

Abstract: In a system having a plurality of caches, a method for maintaining cached objects includes storing an object in a plurality of caches. In response to a request to update the object, a future invalidation time is determined when the object should be invalidated in caches currently storing the object. Updating of the object is delayed until the invalidation time has passed.

Abstract: The present invention concerns methods and apparatus for implementing a multi-user advance reservation system where reservations are specified in terms of flexible constraints, inflexible constraints and business values. The specification of reservations in this manner allows an entity managing the reservation system to arbitrate among reservations received from a user population with a view toward maximizing business value across the user population. In methods and apparatus of the present invention, penalties and rewards associated with various reservation outcomes can be specified in reservations to assist in business value maximization. In an example, a reservation having a low business value may be declined when there is a significant possibility that a reservation having a high business would be submitted during the pendency of service delivery to the user issuing the reservation with a low business value.

Abstract: A system and method for disseminating policies to multiple policy-based components includes a policy producer which generates a group of policies to be enforced. A policy disseminator classifies each policy with a type, and for each policy type, the policy disseminator identifies policy-based components that handle a corresponding policy type. The policy disseminator sends specific policy types from the group of policies to each policy-based component that can handle that specific policy type.

Abstract: Techniques for selectively off-loading workload across multiple data centers are disclosed. For example, a technique for processing a user request in accordance with a multiple data center environment comprises the following steps/operations. A user request is obtained at a first data center. The user request is classified based on one or more classification criterion. At least a portion of a workload associated with the classified user request is off-loaded to at least a second data center to be processed, wherein the off-loading step/operation is at least based on one or more administrative policies associated with at least one of the first data center and the second data center. The workload is processed such that the user request is at least substantially satisfied in accordance with a service level agreement for the requesting user.

Abstract: A technique for tracking a state of one or more input/output (I/O) channels associated with an application, by the application itself, comprises the steps of: (i) storing, by an operating system kernel, one or more selected elements of the state of at least a portion of the one or more I/O channels associated with the application in a memory which is shared by the application and the operating system kernel, when the one or more elements are available to the operating system kernel; (ii) acquiring, by the application, at least a portion of the stored elements through one or more memory read operations of the shared memory; and (iii) assessing, by the application, one or more of the acquired elements to determine the state of the one or more I/O channels corresponding thereto. In this manner, a need for context switching to track the state of the one or more I/O channels is thereby eliminated.

Abstract: Transferring content between one or more input streams and one or more output streams via an application running on a host system. A kernel-level service is provided which is adapted to perform application-specific processing and which attends to transfer of content from at least one input stream to at least one output stream. With the kernel-level service, an operation is performed for the collection of at least one input stream and at least one output stream via: performing application-specific processing; and attending to the transfer of content from at least one input stream to at least one output stream.

Abstract: The present invention is directed to a user-level thread scheduler that employs a service that propagates at the user level, continuously as it gets updated in the kernel, the kernel-level state necessary to determine if an I/O operation would block or not. In addition, the user-level thread schedulers used systems that propagate at the user level other types of information related to the state and content of active file descriptors. Using this information, the user-level thread package determines when I/O requests can be satisfied without blocking and implements pre-defined scheduling policies.

Abstract: A system and method for maintaining consistency in a system where multiple copies of an object may exist is provided for maintaining consistent copies. Consistency is maintained using a plurality of consistency policies in which at least one consistency policy results in different performance than a second consistency policy. A consistency policy is selected from the plurality consistency policies for each object to improve system performance.

Abstract: In a system having a plurality of caches, a method for maintaining cached objects includes storing an object in a plurality of caches. In response to a request to update the object, a future invalidation time is determined when the object should be invalidated in caches currently storing the object. Updating of the object is delayed until the invalidation time has passed.

Abstract: A system and method for maintaining objects in storage elements includes maintaining information regarding which storage elements are storing particular objects and responding to a request to update an object by using maintained information to determine which of the storage elements store a copy of the object. Each storage element is instructed to invalidate the copy of the object, and an update of the object is performed after each storage element that includes the copy of the object indicates that the storage element has invalidated the copy of the object or the storage element is determined to be unresponsive.

Abstract: The present invention provides predictable scheduling of programs using a repeating precomputed schedule. In a preferred embodiment, a scheduler accesses an activity scheduling graph. The activity scheduling graph is comprised of nodes each representing a recurring execution interval, and has one root, one or more leaves, and at least one path from the root to each leaf. Each node is on at least one path from the root to a leaf, and the number of times the execution interval represented by each node occurs during the traversal of the graph is equal to the number of paths from the root to a leaf that the node is on. Each node has associated with it an execution interval length, and is adapted to being dedicated to executing the threads of a single activity. The scheduler first selects a current node within the accessed scheduling graph.

Abstract: A technique for tracking a state of one or more input/output (I/O) channels associated with an application, by the application itself, comprises the steps of: (i) storing, by an operating system kernel, one or more selected elements of the state of at least a portion of the one or more I/O channels associated with the application in a memory which is shared by the application and the operating system kernel, when the one or more elements are available to the operating system kernel; (ii) acquiring, by the application, at least a portion of the stored elements through one or more memory read operations of the shared memory; and (iii) assessing, by the application, one or more of the acquired elements to determine the state of the one or more I/O channels corresponding thereto. In this manner, a need for context switching to track the state of the one or more I/O channels is thereby eliminated.

Abstract: The present invention provides predictable scheduling of programs using a repeating precomputed schedule. In a preferred embodiment, a scheduler accesses an activity scheduling graph. The activity scheduling graph is comprised of nodes each representing a recurring execution interval, and has one root, one or more leaves, and at least one path from the root to each leaf. Each node is on at least one path from the root to a leaf, and the number of times the execution interval represented by each node occurs during the traversal of the graph is equal to the number of paths from the root to a leaf that the node is on. Each node has associated with it an execution interval length, and is adapted to being dedicated to executing the threads of a single activity. The scheduler first selects a current node within the accessed scheduling graph.

Abstract: A method, which may be implemented by a program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for satisfying requests between a client and a server including the steps of providing a first entity with a directory of information about contents of a cache of a second entity, the first entity for receiving a request from a client, determining whether the directory of information indicates that the request is satisfied by the cache of the second entity by querying the directory of information on the first entity, sending the request to the second entity, if the directory indicates that the request is satisfied by the cache of the second entity, and otherwise, sending the request to be satisfied by another entity. A system is also included.

Abstract: The present invention provides predictable scheduling of programs using a repeating precomputed schedule. In a preferred embodiment, a scheduler accesses an activity scheduling graph. The activity scheduling graph is comprised of nodes each representing a recurring execution interval, and has one root, one or more leaves, and at least one path from the root to each leaf. Each node is on at least one path from the root to a leaf, and the number of times the execution interval represented by each node occurs during the traversal of the graph is equal to the number of paths from the root to a leaf that the node is on. Each node has associated with it an execution interval length, and is adapted to being dedicated to executing the threads of a single activity. The scheduler first selects a current node within the accessed scheduling graph.