Many garbage-collected systems use a single garbage collection algorithm across all applications. It has long been known that this can produce poor performance on applications for which that collector is not well suited. In some systems, such as those that execute stand-alone compiled executables, an appropriate collector for each application can be selected from a pool of available collectors and tuned by using profile information. In a study of 20 benchmarks and several collectors, compiled with the Marmot optimizing Java-to-native compiler, for every collector there was at least one benchmark that would have been at least 15% faster with a more appropriate collector. The collectors are a copying collector, a generational copying collector, which is combined with each of 4 different write barriers, and the null collector, which allocates but never collects. A detailed analysis of storage management costs shows how they vary by application and collector.

The Marmot system is a research platform for studying the implementation of high level programming languages. It currently comprises an optimizing native-code compiler, runtime system, and libraries for a large subset of Java. Marmot integrates well-known representation, optimization, code generation, and runtime techniques with a few Java-specific features to achieve competitive performance. This paper contains a description of the Marmot system design, along with highlights of our experience applying and adapting traditional implementation techniques to Java. A detailed performance evaluation assesses both Marmot's overall performance relative to other Java and C++ implementations, and the relative costs of various Java language features in Marmot-compiled code. Our experience with Marmot has demonstrated that well-known compilation techniques can produce very good performance for static Java applications – comparable or superior to other Java systems, and approaching that of C++ in some cases. Copyright © 2000 John Wiley & Sons, Ltd.

Tiger is a scalable, fault-tolerant video file server constructed from a collection of computers connected by a switclied network.,All content files are striped across all of the computers and disks in a Tiger system.In order to prevent conflicts for a particular resource between two viewers, Tiger schedules viewers so that ihey do not require access to the same resource at the same time.In the abstract, there is a single, global schedule that describes all of the viewers in the system.In practice, the schedule is distrib&d among all of the computers in the system, each of which has a possibly partially inconsistent view of a subset of the schedule.By using such a relaxed consistency model for the schedule, Tiger achieves scalability and fault tolerance while still providing $e consistent, coordinated service required by viewers.

Multiprocessor memory reference traces provide a wealth of information on the behavior of parallel programs.We have used this information to explore the relationship between kernel-based NUMA management policies and multiprocessor memory architecture.Our trace analysis techniques employ an off-line, optimal cost policy as a baseline against which to compare on-line policies, and as a policyinsensitive tool for evaluating architectural design alternatives.We compare the performance of our optimal policy with that of three implementable policies (two of which appear in previous work), on a variety of applications, with varying relative speeds for page moves and local, global, and remote memory references.Our results indicate that a good NUMA policy must be chosen to match its machine, and confirm that such policies can be both simple and effective.They also indicate that programs for NUMA machines must be written with care to obtain the best performance.

Multiprocessors with non-uniform memory access times introduce the problem of placing data near the processes that use them, in order to improve performance. We have implemented an automatic page placement strategy in the Mach operating system on the IBM ACE multiprocessor workstation. Our experience indicates that even very simple automatic strategies can produce nearly optimal page placement. It also suggests that the greatest leverage for further performance improvement lies in reducing false sharing, which occurs when the same page contains objects that would best be placed in different memories.

The integration of virtual memory management and interprocess communication in the Accent network operating system kernel is examined. The design and implementation of the Accent memory management system is discussed and its performance, both on a series of message-oriented benchmarks and in normal operation, is analyzed in detail.

No abstract available.