Download presentation
Presentation is loading. Please wait.
1
Communication Scheduling for Time-Triggered SystemsSlide 1 Communication Scheduling for Time-Triggered Systems Paul Pop, Petru Eles and Zebo Peng Dept. of Computer and Information Science Linköping University Sweden
2
Communication Scheduling for Time-Triggered SystemsSlide 2 Conditional Process Graph P4P4 P4P4 P5P5 P5P5 P7P7 P7P7 P 13 P 15 First processor Second processor ASIC C C DD P0P0 P 18 P1P1 P1P1 P2P2 P2P2 P3P3 P3P3 P6P6 P6P6 P8P8 P8P8 P9P9 P9P9 P 10 P 11 P 12 P 14 P 16 P 17 C K K P0P0 P 18 P1P1 P2P2 P3P3 P6P6 P8P8 P9P9 P 10 P 11 P 12 P 14 P 16 P 17 Subgraph corresponding to D C K
3
Communication Scheduling for Time-Triggered SystemsSlide 3 Hardware Architecture I/O Interface TTP Controller CPU RAM ROM ASIC S0S0 S1S1 S2S2 S3S3 S0S0 S1S1 S2S2 S3S3 TDMA Round Cycle of two rounds Slot Node Safety-critical distributed embedded systems. Nodes connected by a broadcast communication channel. Nodes consisting of: TTP controller, CPU, RAM, ROM, I/O interface, (maybe) ASIC. Communication between nodes is based on the time-triggered protocol. Buss access scheme: time-division multiple- access (TDMA). Schedule table located in each TTP controller: message descriptor list (MEDL).
4
Communication Scheduling for Time-Triggered SystemsSlide 4 Problem Formulation Input Safety-critical application with several operating modes. Each operating mode is modelled by a conditional process graph. The system architecture and mapping of processes to nodes are given. The worst case delay of a process is known: Output Local schedule tables for each node and the MEDL for the TTP controllers. Delay on the system execution time for each operating mode, so that this delay is as small as possible.
5
Communication Scheduling for Time-Triggered SystemsSlide 5 Scheduling Example P1P1 P1P1 P4P4 P4P4 P2P2 P2P2 P3P3 P3P3 m1m1 m2m2 m3m3 m4m4 S1S1 S0S0 Round 1Round 2Round 3Round 4Round 5 P1P1 P4P4 P2P2 m1m1 m2m2 m3m3 m4m4 P3P3 Round 1 P1P1 Round 2Round 3Round 4 S1S1 S0S0 m1m1 m2m2 m3m3 m4m4 P2P2 P3P3 P4P4 Round 1Round 2Round 3 S1S1 S0S0 P2P2 P3P3 P4P4 P1P1 m1m1 m2m2 m3m3 m4m4 24 ms 22 ms 20 ms
6
Communication Scheduling for Time-Triggered SystemsSlide 6 Experimental Results Average percentage deviations from the lengths of near-optimal schedules The Greedy Approach is producing accurate results in a very short time (few seconds for graphs with 400 processes). Greedy 1 performs slightly better than Greedy 2, but it is a bit slower. SA finds near-optimal results in a reasonable time (few minutes for graphs with 80 processes and 275 minutes for graphs with 400 processes). A real-life example implementing a vehicle cruise controller validated our approach. % Number of processes
Similar presentations
© 2024 SlidePlayer.com Inc.
All rights reserved.