The test application

The test application is named rt_linux_tutorial. Its architecture consists of a control thread that performs random pointer chasing to simulate a workload and measures wake up jitter, execution time and cache misses. The application also features a statistics handler thread that processes and logs timing information. The statistics are either output to the console via STDOUT or published to an MQTT broker.

High-level design of the test application

Note

The pointer chasing buffer size should exceed the L2 cache size of your processor to see an improvement by cache partitioning described later in this tutorial. You can change the buffer size in rt_linux_tutorial.c by editing the WORKLOAD_BUFFER_SIZE definition.

Build the test application

To build the application, you need Makefile support, the GCC compiler, the Paho MQTT library, and the cJSON library:

sudo apt install make gcc libpaho-mqtt-dev libcjson-dev

The source code for the test application is available in the code archive you downloaded earlier. Make any required changes to the C program code, such as modifying the WORKLOAD_BUFFER_SIZE. Then compile the application using the provided Makefile:

ubuntu@ubuntu:~/tutorial-intel-tcc-code$ make

gcc -Wall -Wextra -O2 -I/usr/local/include   -c -o rt_linux_tutorial.o rt_linux_tutorial.cgcc -Wall -Wextra -O2 -I/usr/local/include -c pointer_chasing.cgcc -Wall -Wextra -O2 -I/usr/local/include -o rt_linux_tutorial rt_linux_tutorial.o pointer_chasing.o -L/usr/local/lib -lpaho-mqtt3c -lcjson

Run the resulting binary with the -h flag to see a summary of options:

ubuntu@ubuntu:~/tutorial-intel-tcc-code$ ./rt_linux_tutorial -h

Usage: rt_linux_tutorial [OPTIONS]Options:  -h        Display this help message  -i <time> Set the cycle time of the control thread in microseconds - default is 500us  -s <0|1>  Set the output method for statistics (0 for stdout, 1 for MQTT to localhost) - default stdout

Run it with MQTT support.

sudo ./rt_linux_tutorial -i 1000 -s 1

Data should start appearing on the Grafana dashboard.

Troubleshooting

If you don’t see any data on the Grafana dashboard, check the data flow and resolve any errors displayed in the messages and/or logs.

Subscribe to the Mosquitto broker

mosquitto_sub -t '#'

You should see a continuous stream of JSON data, that looks similar to this:

{"exec_time":170852,"wakeup_jitter":6592,"cache_misses":0,"ipc":0.036748599261045456}

Check Telegraf logs

cd tutorial-intel-tcc-code/docker-compose/
docker compose logs -f telegraf

You should see the startup sequence of Telegraf, loading InfluxDB as output plugin and MQTT as input. There should not be any errors in the log.

telegraf | I! Loaded outputs: influxdb
...
telegraf | I! [inputs.mqtt_consumer] Connected [tcp://mosquitto:1883]

Check InfluxDB logs

cd tutorial-intel-tcc-code/docker-compose/
docker compose logs -f influxdb

InfluxDB prints logs for all queries that are done on the database. If the Grafana dashboard is open, you should see new logs appearing every 5 seconds, showing the queries made by Grafana. Data that is written to the database is also logged.

influxdb | "GET /query?db=tcc_tutorial_data&epoch=ms&q=SELECT+last%28%22cache_misses%22%29+FROM+%22mqtt_consumer%22+WHERE+time+%3E%3D+1740395727546ms+and+time+%3C%3D+1740396027546ms+GROUP+BY+time%28200ms%29+fill%28null%29+ORDER+BY+time+ASC HTTP/1.1" 200 3898 "-" "Grafana/11.5.2" 5995cb04-f2a1-11ef-8488-0242ac120002 10180
influxdb | "POST /write?db=tcc_tutorial_data HTTP/1.1 " 204 0 "-" "Telegraf/1.33.2 Go/1.23.5" 5a0a00b6-f2a1-11ef-8489-0242ac120002 14423