1 / 9

ECEN 4623/5623 RT Embedded Systems

ECEN 4623/5623 RT Embedded Systems. Mid-Term Review Lecture. MT Review. Fundamentals of RT Analysis RT Correctness – Before Deadline and Correct Result Best Effort, Hard RT, Isochronal RT, and Soft RT Utility Curves for each of the above

Download Presentation

ECEN 4623/5623 RT Embedded Systems

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. ECEN 4623/5623RT Embedded Systems Mid-Term Review Lecture

  2. MT Review • Fundamentals of RT Analysis • RT Correctness – Before Deadline and Correct Result • Best Effort, Hard RT, Isochronal RT, and Soft RT • Utility Curves for each of the above • CPU, I/O, and memory resource space (CPU-bound, I/O-bound, memory/CPU trade-offs) • Basic Timing Diagrams • Theorem 1 – RM Least Upper Bound • Theorem 2 (Lehoczky, Shah, Ding) – If deadline(s) are met over longest period from C.I., then system is feasible • Fixed priority, preemptive, run-to-completion scheduling • Services and interference (interrupts and higher prio services) • Necessary and Sufficient feasibility means?

  3. MT Review • Deadline Monotonic Theory • DM priority assignment policy • Simple sufficient feasibility test • Improved (more necessary) feasibility test • Differences between RM and DM theory • T not equal to D • Priority assignment policy • Iterative feasibility test

  4. MT Review • Rate Monotonic Theory • RM priority assignment policy (optimality is ?) • Liu and Layland Assumptions • C = WCET • T=D • Critical Instant • Others? • RM Feasibility test is ? • Derivation of 2 task RM sufficient LUB • LUB is O(C) complexity – equation • Sufficient, but not Necessary and Sufficient • Dynamic Priority Theories • EDF • Least Laxity

  5. MT Review • Tornado / VxWorks • Diagram of Host-Target IDE • Cross compilation • Target agent (WDB) • Target server (tgtsvr) • Target-Host communication (ethernet, serial, JTAG/BDM) • Dynamic linking and loading • Downloadable ELF modules • Module manager, loader/unloader • built-in target symbol table? • Host-based symbol table? • Host-and-target symbol table with synchronization? • logMsg versus printf • Printf I/O delays caller and can’t be called in kernel/ISR context • logMsg performs output in slack time via tlogTask and message queue interface

  6. MT Review X-window system Interval timer X-interface Control Callback X-display update {time-stamp read} {time-stamp} Windview Wind Kernel WTX-App-Cmd WTX-App-Data {wvOn, wvOff} Trace-data Target server Target agent WTX-Cmd WTX-Data WDB-Data WDB-Cmd Host Link Target Link Link Data Relay

  7. MT Review • RT Synchronization • Priority Inversion • Unbounded Priority Inversion • Priority Inheritence • Priority Ceiling • Necessary 3 Conditions for Unbounded Prio Inversion • 3 or more tasks (H, M, L priority) • H and L tasks involved in mutex • 1 or more M tasks not involved in mutex cause interference • Mars Pathfinder Story • What went wrong? • Why? • How was it fixed?

  8. MT Review • VxWorks Kernel Mechanisms • Basic Task Control – taskLib • VxWorks task states (see Programmer’s Guide) • Creation, Deletion, and Control • Basic Synchronization – semLib • POSIX RT Extensions • Message queues • Priority enqueue and dequeue • Same priority? • Blocking vs. non-blocking send and receive • Real-time signals • Signals that queue – why? • Passing data – how? • Real-Time interval timers and clocks • Systems tick and interval timer jiffy • Hardware interval timer operation • Virtual timers built on hardware interval timer(s)

  9. MT Review • Estimating and Measuring C (WCET) • Windview analysis • Kernel instrumentation (store event ID and time-tag in trace buffer at key locations – e.g. context switch) • Dump trace-buffer in slack time to host • Post-analyze • Estimating C on RISC architectures • Pipelining and superscalar processing • CPI • Cache hit/miss ratio (I-cache and D-cache) • Pipeline stalls • Page faults • WCET

More Related