Requirements to embedded systems increase steadily. In parallel, also the performance of the processors used in these systems is improved leading to multithreaded and/or multicore architectures. Depending on the type of the embedded system, using Java is a more and more popular way for software development. In this paper, we present a Java benchmark suite that enables the comparison of different embedded Java platforms while solely assuming the availability of a CLDC API, the minimal configuration defined for the J2ME. The core of the benchmark suite consists of adapted realworld applications. Furthermore, the suite contains benchmarks to explore multi-core/multi-threaded systems. Hence, it is possible to determine the gain of a parallel execution platform compared to sequential execution. Additionally, the penalty of a sequential program running on a parallel platform can be measured. Our benchmarks are structured in micro, kernel, application, parallel, and streaming benchmarks. 1.

This paper describes the design, implementation, and experimental evaluation of a modular and extensible Java Virtua l Ma chine (JVM) infra structure, ca lled Jupiter. The infra structure is intended to servea sa vehicle for our resea+ h on scaD0K5 JVMa rchitectures fora 128-processor cluster of PC worksta ions, with support for sha15 memory in softwa65 Jupiter is constructed, usinga building blocka rchitecture, out of ma ny modules withsma ll, simple interfa ces. This flexible structure, simila r to UNIX r shellstha t build complex comma1 pipelines out of discrete progra+1 agr ws the r a id prototyping of ourresea0 h idea by confining cha nges in JVM design toa sma ll number of modules. In spite of this flexibility, Jupiter delivers good performa nce. Experimenta eva ua tion of the current implementa tion of Jupiter using the SPECjvm98 benchma rks showstha t it is ona vera1 2.65 times fa6 er tha n K a ea nd 2.20 slower tha n the Sun Microsystems JDK (interpreter versions only). By providing a flexible JVM infrastructure that delivers competitive performance, we believe we have developed a framework that supports further research into JVM scalability.

The Java programming language, being a portable and safe object-oriented language, has gained much interest among embedded and real-time systems developers. However, standard Java implementations exhibit problems with performance, memory footprint, and predictability. The question is then, are these limitations inherent in the technology? Reviewing run-time aspects and the possibility to compile Java to native code, reveals some real limitations as well as common misconceptions. Investigation of the real limitations shows that for implementing real-time Java on small embedded platforms, native compilation via C is an appropriate solution for many platforms and applications. A revised technique for Java-compatible memory management is proposed to reduce latencies, and linkage of externally generated (C) code with natively compiled Java is considered in a prototype that has been implemented. Based on application demands and experimental verification, we find that real-time Java can, and should, retain the standard simple Java memory model to the programmer.

While managed languages such as C # and Java have become quite popular in enterprise computing, they are still considered unsuitable for hard real-time systems. In particular, the presence of garbage collection has been a sore point for their acceptance for low-level system programming tasks. Realtime extensions to these languages have the dubious distinction of, at the same time, eschewing the benefits of highlevel programming and failing to offer competitive performance. The goal of our research is to explore the limitations of high-level managed languages for real-time systems programming. To this end we target a real-world embedded platform, the LEON3 architecture running the RTEMS real-time operating system, and demonstrate the feasibility of writing garbage collected code in critical parts of embedded systems. We show that Java with a concurrent, real-time garbage collector, can have throughput close to that of C programs and comes within 10 % in the worst observed case on realistic benchmark. We provide a detailed breakdown of the costs of Java features and their execution times and compare to real-time and throughput-optimized commercial Java virtual machines.

Lund UniversityIn dwelling, be close to the land. In meditation, delve deep into the heart. In dealing with others, be gentle and kind. In speech, be true. In work, be competent. In action, be careful of your timing.