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171
Thin Locks: Featherweight Synchronization for Java
, 1998
"... Language-supported synchronization is a source of serious performance problems in many Java programs. Even singlethreaded applications may spend up to half their time performing useless synchronization due to the thread-safe nature of the Java libraries. We solve this performance problem with a new ..."
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Cited by 135 (5 self)
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Language-supported synchronization is a source of serious performance problems in many Java programs. Even singlethreaded applications may spend up to half their time performing useless synchronization due to the thread-safe nature of the Java libraries. We solve this performance problem with a new algorithm that allows lock and unlock operations to be performed with only a few machine instructions in the most common cases. Our locks only require a partial word per object, and were implemented without increasing object size. We present measurements from our implementation in the JDK 1.1.2 for AIX, demonstrating speedups of up to a factor of 5 in micro-benchmarks and up to a factor of 1.7 in real programs. 1 Introduction Monitors [5] are a language-level construct for providing mutually exclusive access to shared data structures in a multithreaded environment. However, the overhead required by the necessary locking has generally restricted their use to relatively "heavy-weight" object...
The Performance Implications of Thread Managment Alternatives for Shared-Memory Multiprocessors. In
- IEEE Transactions on Computers,
, 1989
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First-Class User-Level Threads
- In Proceedings of the Thirteenth ACM Symposium on Operating Systems Principles
, 1991
"... It is often desirable, for reasons of clarity, portability, and efficiency, to write parallel programs in which the number of processes is independent of the number of available processors. Several modern operating systems support more than one process in an address space, but the overhead of creati ..."
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Cited by 124 (12 self)
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It is often desirable, for reasons of clarity, portability, and efficiency, to write parallel programs in which the number of processes is independent of the number of available processors. Several modern operating systems support more than one process in an address space, but the overhead of creating and synchronizing kernel processes can be high. Many runtime environments implement lightweight processes (threads) in user space, but this approach usually results in second-class status for threads, making it difficult or impossible to perform scheduling operations at appropriate times (e.g. when the current thread blocks in the kernel). In addition, a lack of common assumptions may also make it difficult for parallel programs or library routines that use dissimilar thread packages to communicate with each other, or to synchronize access to shared data. We describe a set of kernel mechanisms and conventions designed to accord first-class status to user-level threads, allowing them to be used in any reasonable way that traditional kernel-provided processes can be used, while leaving the details of their implementation to userlevel code. The key features of our approach are (1) shared memory for asynchronous communication between the kernel and the user, (2) software interrupts for events that might require action on the part of a user-level scheduler, and (3) a scheduler interface convention that facilitates interactions in user space between dissimilar kinds of threads. We have incorporated these mechanisms in the Psyche parallel operating system, and have used them to implement several different kinds of user-level threads. We argue for our approach in terms of both flexibility and performance.
A structural view of the Cedar programming environment
- ACM Transactions on Programming Languages and Systems
, 1986
"... This paper presents an overview of the Cedar programming environment, focusing on its overall structure-that is, the major components of Cedar and the way they are organized. Cedar supports the development of programs written in a single programming language, also called Cedar. Its primary purpose i ..."
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Cited by 120 (3 self)
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This paper presents an overview of the Cedar programming environment, focusing on its overall structure-that is, the major components of Cedar and the way they are organized. Cedar supports the development of programs written in a single programming language, also called Cedar. Its primary purpose is to increase the productivity of programmers whose activities include experimental pro-gramming and the development of prototype software systems for a high-performance personal computer. The paper emphasizes the extent to which the Cedar language, with run-time support, has influenced the organization, flexibility, usefulness, and stability of the Cedar environment. It high-lights the novel system features of Cedar, including automatic storage management of dynamically allocated typed values, a run-time type system that provides run-time access to Cedar data type definitions and allows interpretive manipulation of typed values, and a powerful deuice-independent imaging model that supports the user interface facilities. Using these discussions to set the context, the paper addresses the language and system features and the methodologies used to facilitate the integration of Cedar applications. A comparison of Cedar with other programming environments further identifies areas where Cedar excels and areas where work remains to be done.
Pilot: An Operating System for a Personal Computer
, 1980
"... this paper was presented at the 7th ACM Symposium on Operating Systems Principles, Pacific Grove, Calif., Dec. 10-12, 1979 ..."
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Cited by 101 (2 self)
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this paper was presented at the 7th ACM Symposium on Operating Systems Principles, Pacific Grove, Calif., Dec. 10-12, 1979
Smart Packets for Active Networks
, 1998
"... Smart Packets is a DARPA-funded Active Networks project focusing on applying active networks technology to network management and monitoring without placing undue burden on the nodes in the network. Messages in active networks are programs that are executed at nodes on the path to one or more target ..."
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Cited by 94 (1 self)
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Smart Packets is a DARPA-funded Active Networks project focusing on applying active networks technology to network management and monitoring without placing undue burden on the nodes in the network. Messages in active networks are programs that are executed at nodes on the path to one or more target hosts. Smart Packets programs are written in a tightly-encoded, safe language specifically designed to support network management and avoid dangerous constructs and accesses. Smart Packets improves the management of large complex networks by (1) moving management decision points closer to the node being managed, (2) targeting specific aspects of the node for information rather than exhaustive collection via polling, and (3) abstracting the management concepts to language constructs, allowing nimble network control. This paper introduces Smart Packets and describes the Smart Packet architecture, the packet formats, the language and its design goals, and security considerations. Keywords--...
Commutativity Analysis: A New Analysis Technique for Parallelizing Compilers
- ACM TRANSACTIONS ON PROGRAMMING LANGUAGES AND SYSTEMS
, 1997
"... This article presents a new analysis technique, commutativity analysis, for automatically parallelizing computations that manipulate dynamic, pointer-based data structures. Commutativity analysis views the computation as composed of operations on objects. It then analyzes the program at this granula ..."
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Cited by 87 (11 self)
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This article presents a new analysis technique, commutativity analysis, for automatically parallelizing computations that manipulate dynamic, pointer-based data structures. Commutativity analysis views the computation as composed of operations on objects. It then analyzes the program at this granularity to discover when operations commute (i.e., generate the same final result regardless of the order in which they execute). If all of the operations required to perform a given computation commute, the compiler can automatically generate parallel code. We have implemented a prototype compilation system that uses commutativity analysis as its primary analysis technique
Scheduling Garbage Collection in Embedded Systems
, 1998
"... The complexity of systems for automatic control and other safety-critical applications grows rapidly. Computer software represents an increasing part of the complexity. As larger systems are developed, we need to find scalable techniques to manage the complexity in order to guarantee high product qu ..."
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Cited by 83 (0 self)
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The complexity of systems for automatic control and other safety-critical applications grows rapidly. Computer software represents an increasing part of the complexity. As larger systems are developed, we need to find scalable techniques to manage the complexity in order to guarantee high product quality. Memory management is a key quality factor for these systems. Automatic memory management, or garbage collection, is a technique that significantly reduces the complex problem of correct memory management. The risk of software errors decreases and development time is reduced. Garbage collection techniques suitable for interactive and soft real-time systems exist, but few approaches are suitable for systems with hard real-time requirements, such as control systems (embedded systems). One part of the problem is solved by incremental garbage collection algorithms, which have been presented before. We focus on the scheduling problem which forms the second part of the problem, i.e. how the work of a garbage collector should be scheduled in order
Scheduling Sporadic Tasks with Shared Resources in Hard-Real-Time Systems
, 1992
"... The problem of scheduling a set of sporadic tasks that share a set of serially reusable, single unit software resources on a single processor is considered. The correctness conditions are that (1) each invocation of each task completes execution at or before a well-defined deadline, and (2) a resour ..."
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Cited by 74 (14 self)
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The problem of scheduling a set of sporadic tasks that share a set of serially reusable, single unit software resources on a single processor is considered. The correctness conditions are that (1) each invocation of each task completes execution at or before a well-defined deadline, and (2) a resource is never accessed by more than one task simultaneously. We present an optimal on-line algorithm for scheduling a set of sporadic tasks. The algorithm results from the integration of a synchronization scheme for access to shared resources with the earliest deadline first algorithm. A set of relations on task parameters that are necessary and sufficient for a set of tasks to be schedulable is also derived. Our model for the analysis of processor scheduling policies is novel in that it incorporates minimum as well as maximum processing time requirements of tasks. The scheduling algorithm and the sporadic tasking model have been incorporated into an operating system kernel and used to impleme...
Static Analyses for Eliminating Unnecessary Synchronization from Java Programs
- IN PROCEEDINGS OF THE 6TH INTERNATIONAL STATIC ANALYSIS SYMPOSIUM
, 1999
"... This paper presents and evaluates a set of analyses designed to reduce synchronization overhead in Java programs. Monitor-based synchronization in Java often causes significant overhead, accounting for 5-10% of total execution time in our benchmark applications. To reduce this overhead, programm ..."
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Cited by 72 (4 self)
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This paper presents and evaluates a set of analyses designed to reduce synchronization overhead in Java programs. Monitor-based synchronization in Java often causes significant overhead, accounting for 5-10% of total execution time in our benchmark applications. To reduce this overhead, programmers often try to eliminate unnecessary lock operations by hand. Such manual optimizations are tedious, error-prone, and often result in poorly structured and less reusable programs. Our approach replaces manual optimizations with static analyses that automatically find and remove unnecessary synchronization from Java programs. These analyses optimize cases where a monitor is entered multiple times by a single thread, where one monitor is nested within another, and where a monitor is accessible by only one thread. A partial implementation of our analyses eliminates up to 70% of synchronization overhead and improves running time by up to 5% for several already hand-optimized benchmarks. Thus, our automated analyses have the potential to significantly improve the performance of Java applications while enabling programmers to design simpler and more reusable multithreaded code.
