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Third Real-Time Linux Workshop Keynotes


  • A Forward Look On Embedded Systems
    Andrea Cuomo
  • Humanoid Robot H7 for Autonomous & Intelligent Software Research
    Satoshi Kagami
  • Measuring Performance in Real-Time Linux
    Fred Proctor

    • A Forward Look On Embedded Systems

    Andrea Cuomo

    Business is changing at an extreme speed. Time to volume and lifetime of products are shrinking, while business models are changing and value chains are moving. The evolution of all market segments reflects and follow the changes in the business scenario: firmware, drivers, middleware, operating systems and application algorithms are affected by the new business rules. They all are facing the challenge to adapt to the new business models. The DSP segment is maybe the most affected by business and market changes. On the technology side, DSPs allow today to have a computational power of 20 GIPs on a piece of silicon whose area is a few tens of square millimeters. On the system side, however, we must take into account the performance and power comsumption requirements of the applications for which each DSP has been designed. The trend is towards application-driven architectures where tools, algorithms and architectures are co-developed, following needs and requirements specific to each application. Operating systems are central to this strategy. And ensuring free competition has to take into account the central role of open source software. Long live Linux !



    Humanoid Robot H7 for Autonomous & Intelligent Software Research

    Satoshi Kagami

    A humanoid robot ``H7'' is developed as a platform for the research on perception-action coupling in intelligent behaviour of humanoid type robots. The H7 has the features as follows : 1) body which has enough DOFs and each joint has enough torque for full body motion, 2) PC/AT compatible high- performance on-board computer which is controlled by RT-linux so that from low-level to high-level control is achieved simultaneously, 3) self-contained and connected to a network via radio ethernet, 4) Online walking trajectory generation with collision checking, 5) motion planning by 3D vision functions are available. The H7 is expected to be a common test-bed in experiment and discussion for various aspects of intelligent humanoid robotics.



    Measuring Performance in Real-Time Linux

    Fred Proctor

    There are many measures of software performance, split between size, speed, and resource use. Linux measures up quite well with these metrics: the kernel is scaleable and small to begin with, and it boots up quickly with a minimum of disk activity. More detailed measures can be made using benchmarks such as those from SPEC. Real-time programmers, however, are more concerned with timing performance against a deadline. Real-time operating systems provide a guarantee that tasks will execute before their deadline, but the question is, how precisely? No matter how well-written, schedulers will eventually run up against timing uncertainties in the underlying hardware due to features such as caches, pipelines, and speculative execution. Various methods of measuring this timing jitter exist. Measurements on the RTL and RTAI variants of real-time Linux show that jitter contributes several to tens of microseconds of variation in task execution. Techniques to minimize these effects can reduce jitter down to below a tenth of a microsecond, for tasks that run at periods of a few tens of microseconds. This analysis and experimental results show that real-time Linux is suitable for fairly aggressive real-time tasks, such as the low-level control of stepper motors.