International Business Machines Corporation

James Bernard Moody

Bruce Gerard Mealey

Thomas Stanley Mathews

Suresh Eswara Warrier

Michael Gerard Mall

Paul Edward McKenney

Larry Bert Brenner

Luke Matthew Browning

Michael E Lyons

A system, and computer usable program product for a dual mode reader writer lock are provided. A contention condition is determined in using an original lock. The original lock manages read and write access to a resource by several processes executing in the data processing system. The embodiment creates a set of expanded locks for use in conjunction with the original lock. The original lock and the set of expanded locks forming the dual mode reader writer lock, which operates to manage the read and write access to the resource. Using an index within the original lock, each expanded lock is indexed such that each expanded lock is locatable using the index. The contention condition is resolved by distributing requests for acquiring and releasing the read access and write access to the resource by the several processes across the original lock and the set of expanded locks.

Dual mode reader writer lock

A method for a dual mode reader writer lock is provided. A contention condition is determined in using an original lock. The original lock manages read and write access to a resource by several processes executing in the data processing system. The embodiment creates a set of expanded locks for use in conjunction with the original lock. The original lock and the set of expanded locks forming the dual mode reader writer lock, which operates to manage the read and write access to the resource. Using an index within the original lock, each expanded lock is indexed such that each expanded lock is locatable using the index. The contention condition is resolved by distributing requests for acquiring and releasing the read access and write access to the resource by the several processes across the original lock and the set of expanded locks.

The illustrative embodiments provide a computer implemented method, apparatus, and computer usable program code for managing a heap. The heap is partitioned into at least one sub heap based on a relationship to at least one memory class of a plurality of memory classes. A memory allocation request comprising a memory class is received from a requester. A unique heap handle based on the memory class and associated with a specific sub heap is generated. The unique heap handle is then returned to the requester.

Memory class based heap partitioning

A method, system, and computer usable program product for retooling lock interfaces for using a dual mode reader writer lock. An invocation of a method is received using an interface. The method is configured to operate on a lock associated with a resource in a data processing system. A determination is made whether the lock is an upgraded lock. The upgraded lock is the DML operating in an upgraded mode. An operation corresponding to the method is executed on the DML, if the lock is the upgraded lock.

Retooling lock interfaces for using a dual mode reader writer lock

A method, system, and computer usable program product for using a dual mode reader writer lock. A contention condition is detected in the use of a lock in a data processing system, the lock being used for managing read and write access to a resource in the data processing system. A determination of the data structure used for implementing the lock is made. If the data structure is a data structure of a reader writer lock (RWL), the data structure is transitioned to a second data structure suitable for implementing the DML. A determination is made whether the DML has been expanded. If the DML is not expanded, the DML is expanded such that the data structure includes an original lock and a set of expanded locks. The original lock and each expanded lock in the set of expanded locks forms an element of the DML.

Using a dual mode reader writer lock

A kernel of a SMT enabled processor system facilitates construction of an exclusive set of processors to simulate an ST mode for handling the tasks of the ST workload, wherein the ST workload runs more efficiently on single threaded processors. The kernel schedules the ST workload on the exclusive set of processors by selecting one hardware thread per processor within said exclusive set of processors to handle a separate one of the tasks of the ST workload, while requiring the remaining hardware threads per processor within the exclusive set to idle. As a result, the ST workload is executed on the SMT enabled processor system as if the exclusive set of processors run in ST mode, but without actually deactivating the remaining idle hardware threads per processor within the exclusive set of processors.

Managing execution of mixed workloads in a simultaneous multi-threaded (SMT) enabled system

A SMT enabled processor system, having multiple processors each activated to interleave execution of multiple hardware threads on each processor, for ST workload, includes a kernel. The kernel of the SMT enabled processor system facilitates construction of an exclusive set of processors to simulate an ST mode for handling the tasks of the ST workload, wherein the ST workload runs more efficiently on single threaded processors. The kernel schedules the ST workload on the exclusive set of processors by selecting one hardware thread per processor within said exclusive set of processors to handle a separate one of the tasks of the ST workload, while requiring the remaining hardware threads per processor within the exclusive set to idle. The ST workload is executed on the SMT enabled processor system as if the exclusive set of processors run in ST mode, but without actually removing the remaining idle hardware threads per processor within the exclusive set of processors.

A method, system and computer program product are provided for representing resource sets in a variable format. Variable resource sets are represented in two parts: a system topology domain and a system detail level. Logical entities are allowed to consume variable resource sets to specify the domain and level required in the attachment. Thus, the resource set attachment is made using a domain system detail level, but the actual resources represented are derived dynamically. That is, the elements that were once statically represented by bits in the resource set are now derived dynamically to reflect the system state at the time they are being used.

Variable resource sets

An apparatus, method and computer program product for minimizing the negative effects that occur when simple locks are highly contended among processors which may or may not have identical latencies to the memory that represents a given lock, are provided. The apparatus, method and computer program product minimize these effects by converting simple locks such that they act as standard simple locks when there is no contention and act as krlocks when there is contention for a lock. In this way, the number of processors spinning on a lock is limited to a single processor, thereby reducing the number of processors that are in a wait state and not performing any useful work.

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Austin, TX, United States of America

James Bernard Moody