International Business Machines Corporation

Wendell W Wilkinson

Jeffrey Mark Nick

David Arlen Elko

David Harold Surman

Peter Grimm Sutton

Mark A Boonie

Phil C Yeh

Dennis J Dahlen

Steven N Goss

Michael J Jordan

Douglas W Westcott

Richard Pervin King

Audrey A Helffrich

Ruth A Allen

Mark A Brooks

Stewart Laundon Palmer

Jeffrey Paul Kubala

Michael D Swanson

Jeffrey William Josten

Jimmy Paul Strickland

Gary M King

Gerard Maclean Dearing

Phil Chi-Chung Yeh

John Charles Nagy

Kelly Scott Carpenter

A coupling facility is coupled to one or more other coupling facilities via one or more peer links. The coupling of the facilities enables various functions to be supported, including the duplexing of structures of the coupling facilities. Duplexing is performed on a structure basis, and thus, a coupling facility may include duplexed structures, as well as non-duplexed or simplexed structures.

Halting execution of duplexed commands

Restarting of coupling facility commands. A restart token is obtained from one coupling facility command and used to restart another coupling facility command. The command from which the restart token is obtained is a different command from the command being restarted. In one example, the command being restarted is a duplexed command.

Restarting a coupling facility command using a token from another coupling facility command

A method and apparatus for dynamically controlling the dispatching of a coupling facility operating in a logical partition sharing a processor resource with one or more other logical partitions issuing requests to the coupling facility. A plurality of coupling facility dispatching modes differing in their relative dispatch duration are defined. One dispatching mode is initially selected, and the number of requests received from the other logical partitions within a predetermined interval while in a selected dispatching mode is determined. Transitions between the defined dispatching modes are made in accordance with the number of requests received within the sampling interval in the selected dispatching mode. The method and apparatus are especially suitable for controlling the dispatching of a backup coupling facility, whose polling loop would otherwise consume processor resources usable by other logical

Method and apparatus for dynamically controlling the execution of a request handler on a processor resource

Method, system and program products for resolving potential deadlocks

Storage structures of a shared storage processor of a computing environment are copied. A copy operation for a storage structure of the shared storage processor is initiated. Although the storage structure is owned by an exploiter of the storage structure, at least a portion of the contents of the storage structure is copied via an operating system of the computing environment. The at least a portion of the contents are copied from the storage structure to another storage structure of the computing environment. Both storage structures may be located within the same shared storage processor or within different shared storage processors.

Method, system and program products for copying coupling facility structures

Cache structures of a shared storage processor of a computing environment are copied. A copy operation for a cache structure of the shared storage processor is initiated. Although the cache structure is owned by an exploiter of the cache structure, one or more objects of the cache structure are copied via an operating system of the computing environment. The one or more objects are copied from the cache structure to another cache structure of the computing environment. Both cache structures may be located within the same shared storage processor or within different shared storage processors.

Method, system and program products for copying coupling facility cache structures

A method and apparatus for serializing access by n entities to a shared resource in an information handling system. A waiter list is defined as a circular list of n bits, each of which is assigned to an entity. When a bit is false (0) it indicates that the corresponding entity is not waiting for the lock; when the bit is true (1) it indicates the corresponding entity is waiting for the lock. A next waiter indicator (NWI) is also defined that contains a value from 0 to n inclusive; a value of 0 indicates that there are currently no waiters, while a value from 1 to n indicates the next waiter to whom the lock will be granted. The waiter list is initialized to zeros to indicate there are no waiters. When an entity requests a lock that cannot be granted, the entity is made a waiter by setting the corresponding bit in the waiter list to one. If the next waiter indicator is zero, indicating that there were previously no waiters for the lock, the indicator is set to identify the requesting entity as the next waiter. When a lock is released and there is a next waiter for the lock as indicated by the next waiter indicator, that waiter is made a lock holder and the corresponding bit in the waiter list is reset to indicate that the entity is no longer a waiter for the lock. A new next waiter is then found by scanning the waiter list beginning with the entry following that for the entity granted access to the resource. This ensures that once a waiter releases a lock, the waiter is not selected to receive the lock again until all other waiters have received the lock.

Method and apparatus for serializing access to a shared resource in an information handling system

Fully-associative non-linear collections of items are browsed. At least a portion of a fully-associative non-linear collection of items is segmented into a plurality of segments. This segmenting is transparent to any browsers of the fully-associative non-linear collection of items. The plurality of segments is then browsed by multiple browsers.

Method, system and program products for browsing fully-associative collections of items

In a network computing environment having a plurality of central processing units, a high performance locking facility coupled to said plurality of central processing units comprising: a processing means for processing multiple requests for locking operations simultaneously and a lock table for creating entries including lock names and lock states. A high-speed searching mechanism for searching any particular lock entry in the table is also provided, as well as means for altering and modifying said table accordingly depending upon any lock status that is being processed. Finally a response and status generator is provided for providing an appropriate response and status of any lock state to other requestors requesting a particular lock.

Apparatus for a high performance locking facility

Changed data of castout classes of a coupling facility cache are managed in order to be able to efficiently determine the age of the oldest changed data in the cache. A directory entry representing a changed datum is placed in a data structure corresponding to the castout class of the changed datum. The data structure includes an order queue ordered by timestamps and a process queue, having an ordered portion and an unordered portion. When the directory entry is to be added to the data structure, an attempt is first made to place the entry on the order queue. If the entry is not placed on the order queue within a predefined amount of time, then the entry is placed on the process queue, the order of which is maintained by background tasks. In order to return the oldest entry of the data structure, the smallest entry of the process queue is determined and that entry is then compared to the smallest entry of the order queue. The smaller of those two entries corresponds to the oldest entry for the castout class.

Method, system and program products for managing changed data of castout classes

A method and apparatus of assigning and releasing locks, in a network computing environment having a plurality of central processing units coupled to a high performance locking facility. The method comprises of the steps of first receiving and processing a lock operation synchronous to any requesting central processor unit requesting a lock and then recording lock names and lock states in entry records of a lock table based on the requests. When a request is being processed, providing high-speed searching to search any particular lock entry in the table and altering and modifying the table accordingly. Finally an appropriate response and the status of the lock state will be generated and sent to other requesters requesting the lock.

Method and apparatus for conducting a high performance locking facility in a loosely coupled environment

A method of assigning and releasing locks, in a network computing environment having a plurality of central processing units coupled to a high performance locking facility. The method comprises of the steps of first processing multiple requests for locking operations simultaneously and then recording lock names and lock states in entry records of a lock table based on the requests. When a request is being processed, providing high-speed searching to search any particular lock entry in the table and altering and modifying the table accordingly. Finally an appropriate response and the status of the lock state will be generated and sent to other requestors requesting the lock.

High performance locking facility

The present invention provides for a computer program product and device including instructions executable by a digital processing apparatus for conducting a high-performance locking facility. At first multiple requests for locking operations are processed and received simultaneously and their lock names and lock states are recorded in entry records of a lock table based on the requests. Next high-speed searching of any particular lock entry in this table is performed followed. The table can be altered and modified at this time as well accordingly depending upon lock status that is being processed. Finally an appropriate response is generated and the status of the lock state is provided to those requesting the lock.

Computer program means and device for conducting high performance

A method and apparatus for optimizing a data structure of an external data storage facility shared by a plurality of data processing systems, the data structure being allocated by a first allocation command which includes first allocation parameters based on an amount of storage space in the external data storage facility assigned for creation of the data structure and a composition of the data structure, includes a device for determining values of the first allocation parameters, to thereby determine a first composition of the data structure, a device for determining an actual usage of the data structure, to thereby determine a second composition of the data structure, a device for comparing the first composition of the data structure with the second composition of the data structure, and a device for issuing, based on an output from the comparing device, a second allocation command having second allocation parameters, to the data structure for reallocation thereof. The issuing device includes a device for adjusting the first composition of the data structure to the second composition, as storage space in the external data storage facility and processing cycles become available to execute the second allocation parameters. Until the second allocation parameters are achieved, the reallocation of the data structure remains pending and all processing commands are accepted and processed by the external data storage facility.

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Hyde Park, NY, United States of America

Wendell W Wilkinson