ECalls (Event Calls) - User/Kernel Interface for Extensible Operating
Systems
To gain substantial performance for embedded systems, it must be possible
to extend these systems at runtime. That is, rather than requiring that all
system functionality is present at all times, it should be possible to configure
these systems at runtime, by addition of real-time functionality, by inclusion
of application-level code with OS kernels, etc. These facts are well-known
in the embedded domain, having led to the inclusion of many load-time configuration
options for commercial platforms like VxWorks.
Our project seeks to perform runtime configuration and fine-grain configuration
of embedded software. The idea is to permit unprivileged (not `superuser')
to add or modify services provided by the operating system kernel.
Toward this end, we have developed ECalls, a lightweight facility for event-based,
synchronous or asynchronous user/kernel
communication. ECalls (Event Calls) addresses several issues in user/kernel
communication: it delivers events from kernel to application and vice versa
while (1) offering several different methods of control transfer with different
real-time characteristics, (2) implementing a hierarchical scheduler which
integrates the scheduling of tasks and events, (3) using data structures
locked into memory and shared between kernel services and application to
avoid explicit data passing, and (4) reducing the frequency of control transfers
with filters, delayed system calls, and batched system calls.
Publications:
- Christian Poellabauer, Karsten Schwan, and Richard
West, "Coordinated CPU and Event Scheduling for Distributed Multimedia
Applications", Proceedings of the 9th ACM Multimedia Conference,
Ottawa, Canada, October 2001.
Postscript |
PDF Format
- Christian Poellabauer, Karsten Schwan, and Richard
West, "Lightweight Kernel/User Communication for Real-Time and Multimedia
Applications", Proceedings of the 11th International Workshop on
Network and Operating Systems Support for Digital Audio and Video (NOSSDAV
2001), Port Jefferson, NY, June 2001.
Postscript |
PDF Format
- Christian Poellabauer, Karsten Schwan, Richard
West, Ivan Ganev, Neil Bright, and Gregory Losik, "Flexible User/Kernel
Communication for Real-Time Applications in ELinux", Proceedings
of the Workshop on Real Time Operating Systems and Applications and Second
Real Time Linux Workshop (in conjunction with RTSS 2000), Orlando,
FL, November 2000.
Postscript |
PDF Format