Embedded Computing Design August 2011 : Page 35Direct Java bytecode execution With direct Java bytecode execution, the JVM bytecodes are the proces-sor’s instruction set. Their executions are fast and atomic (non-interruptible). Interpretation and Just-In-Time (JIT) compilation are not required. This inno-vation allows: ❯ Fast Java bytecode execution: No slowdown by interpretation or JIT compilation. ❯ Low memory footprint: Interpreter and JIT compilation adds to the memory requirement. ❯ Low power consumption: Can use lower clock due to higher Java performance. ❯ Low cost: No JVM interpreter or JIT compiler license cost. Figure 1 illustrates the contrast between direct execution and traditional Java implementations. [Figure 1 | Direct Java bytecode execution offers lower memory footprint, power consumption, and costs compared to traditional JVMs.] Java Bytecode Java Bytecode Java Bytecode Java Bytecode JVM Interpreter RTOS General CPU Interpreter Slow Medium Memory External OS JVM JIT Compiler Partial JVM Interpreter RTOS Other Java Silicon Java execution (60%) Medium fast Small Memory External OS Java Direct Execution Silicon Direct execution (100%) Fastest Smallest Memory Embedded OS RTOS General CPU JIT compiler Fast Large Memory External OS Figure 1 | Direct Java bytecode execution offers lower memory footprint, power consumption, and costs compared to traditional JVMs. Hardware Real-Time Operating System (RTOS) Real-time Java is achieved with native hardware implementation of real-time Java threading primitives, deterministic threading, a fixed-priority preemptive thread scheduler, and automatic interrupt vectoring. Without hardware real-time Java, a dual language platform must be employed (C for real-time functions and Java for non-real-time functions), result-ing in high development and maintenance costs to support two programming lan-guages and environments. The weak link between C and Java inherent in the dual language platform is also a key source of security issues. Eliminating this weak link makes the processor less prone to crashes, hacking, or virus attacks. This innovation allows: ❯ Hard real time: Standard Java programs can use real-time features automatically. ❯ Low memory footprint: The RTOS is built in and does not require an external RTOS, which adds to the memory requirement. ❯ Low cost: No external RTOS licensing cost. www.embedded-computing.com Embedded Computing Design Resource Guide August 2011 | 35 ATP Electronics |
