The Timed C E2E Toolchain

The Timed C E2E is a pragmatic toolchain that takes as input a Timed C program and performs temporal (schedulability and sensitivity) analysis on the program. The Timed C E2E toolchain integrates :

1. KTC source-to-source compiler: A source to source compiler for compiling Timed C program to target specific C code.
2. Schedulability test tool : A tool that performs schedulability tests for sets of non-preemptive jobs.
3. Sensitivity analysis tool : A tool that computes the weakly hard constraint of a system w.r.t WCET margins.

The Timed C E2E toolchain takes as input a Timed C program and does the following steps in order:

1. KTC Profiling : performs measurement-based WCET estimations using the KTC profiler. The KTC profiler is an extension of the KTC compiler. It takes as input a Timed C program and generates an instrumented C program. It then automatically compiles this instrumented C code and calculates the WCET. It uses this information to generate input for the next step.
2. Schedulability Test : uses this estimates to perform schedulability test. The tool also supports uniprocessor analysis with abort actions, which forcefully stops and discards a job's execution at its deadline.
3. Sensitivity Analysis : based on the ouput from the previous step it performs temporal sensitivity analysis. It calculates the maximum scaling factor and M for a given k

References:

1. Timed C :: S. Natarajan and D. Broman, “Timed C : An Extension to the C Programming Language for Real-Time System”, In 2018 IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS). IEEE, 2018.
2. Schedulability Test :: M. Nasri and B. Brandenburg, “An Exact and Sustainable Analysis of Non-Preemptive Scheduling” , Proceedings of the 38th IEEE Real-Time Systems Symposium (RTSS 2017), pp. 12–23, December 2017. M. Nasri, G. Nelissen, and B. Brandenburg, “A Response-Time Analysis for Non-Preemptive Job Sets under Global Scheduling”, Proceedings of the 30th Euromicro Conference on Real-Time Systems (ECRTS 2018), pp. 9:1–9:23, July 2018.

Installing Timed C E2E toolchain

The Timed C e2e toolchain is packed as an docker image. This makes the e2e toochain portable across different operating systems. This document describe how to install the e2e toolchain as a docker image. This docker container is known to work on Ubuntu, Linux, and Windows machines.

Installing Docker

If the docker sofware is installed on your machine please skip this step. Otherwise, follow the instruction below

For Windows

https://docs.docker.com/docker-for-windows/install/

For Ubuntu

https://docs.docker.com/install/linux/docker-ce/ubuntu/

For Mac OS

https://docs.docker.com/docker-for-mac/install/

Installing the Timed C E2E Docker Image

1. Clone from the Timed C E2E repo

    git clone https://github.com/saranya-natarajan/end-to-end-toolchain.git
   

2. Enter the working directory and fetch submodules

    cd end-to-end-toolchain
    git submodule init
    git submodule update
   

If you get a error on update please use the below command

	git submodule update --force --recursive --init --remote 

3. Build the E2E docker image. This will take few minutes.

    docker build --no-cache --tag=e2e .
   

Updating the Timed C E2E Toolchain

Note : do this only after your initial installation is done successfully.

1. Pull from the Timed C E2E repo

    git pull
   

2. Enter the working directory and fetch update submodules

    git submodule update
   

3. Re-build the E2E docker image

    <path-to-end-to-end-toolchain>/end2end --end
    docker build --no-cache --tag=e2e .
   

Running the toolcahin

Run the docker image

<path-to-end-to-end-toolchain>/end2end --init

Compiling timed C code for freeRTOS platform.

	<path-to-end-to-end-toolchain>/bin/ktc <file.c> --freertos

Compiling timed C code for POSIX platform

	<path-to-end-to-end-toolchain>/bin/ktc <file.c> --posix

Compiling timed C code for profiling (complete timing trace). Here iter is the number of iteration. Output is cil.c file

	<path-to-end-to-end-toolchain>/bin/ktc <file.c> --posix --timing-trace <iter>

Compiling timed C code for profiling (only parameters). Here iter is the number of iteration. Output is cil.c file

	<path-to-end-to-end-toolchain>/bin/ktc <file.c> --posix --timing-param <k> <iter>

Compile and run timed C code for profiling . Here iter is the number of iteration. Output is cil.c file

	<path-to-end-to-end-toolchain>/bin/ktc <file.c> --posix-run --timing-param <k> <iter>

Run sensitivity analysis

	<path-to-end-to-end-toolchain>/bin/sens <file> <trace-format> <kfile> <epsilon> <utilization_cap>  --util <policy>

where, trace-format is --param or --trace, epsilon is epsilon resolution, utilization_cap is the cap on system utilization and policy is either 0 for edf and 1 for RM. kfile is a csv file that list the name of a tasks, its k, and its limit of interest (task name,k,l),

The Format of the Output File

Below is an example depicting M v/s WCET margins for a given input

Misses 	WCET Margin
0		0.419789309955
3		0.508166006787
5		0.530260180995
7		0.59654270362
19		0.640731052036
22		0.662825226244
26		0.684919400452