IFogSim features questions

[klementc]

Hello, I am trying to use IFogSim to simulate fog scenarios. Because I don't find a lot of documentation, I have a few questions about IFogSim's models and how to measure some performance metrics.

• Measuring the duration of a microservice request execution: To obtain the start and finish times of a single microservice execution I use the methodstuple.getSubmissionTime() and tuple.getFinishTime(). Are these appropriate or should I measure request execution duration with other methods?
• Measuring the communication duration between two services: To obtain these values, I log information in the sendUpFreeLink/sendUp and sendDownFreeLink/sendDown of FogDevice.java for the start of transmission, and the arrival time in ProcessTupleArrival of FogDevice.java. Is this approach appropriate or should I measure request transmission durations with other methods?
• Multicore processing: I tried to create a microservice executing on a fog device with 2 cores by adding another PE in its PEList. However, executions only take place on the first core of the machine. Is it possible to execute concurrently two requests on two different cores?
• ShedulingInterval: FogDevice creation has a double schedulingInterval parameter. I observe its value is 10 in most examples, and a value of 0 leads to an infinite loop. I did not find a reference explaining how to set this value. Can you explain this parameter so that I can use it correctly?
• Communication link: When sending two messages from a device at the same time, I observe they are sent one after the other. It seems to match the network model for communications in IFogSim defined in FogDevice.java. Is there an option to send the two messages concurrently so they arrive at the same time (but take twice as long to be sent)?
• Wi-Fi: In the published research paper: iFogSim2: An extended iFogSim simulator for mobility, clustering, and microservice management in edge and fog computing environments, case study 2 (Cardiovascular Health Monitoring) mentions the use of Wi-Fi gateways:a physical topology of 7 Fog nodes is used, which consists of 6 Wifi gateways (tier-2 nodes) [...] Also, 25 smartphones with randomly generated locations connect with the Wifi gateways to send ECG sensor data I did not find information on whether or not Wi-Fi communications differ from Wired communications in IFogSim. Do the Wi-Fi nodes share a common communication link when they communicate (so they cannot communicate two at a time with their gateway) or not? If they are different, how do I define a set of Wi-Fi stations and their access point?
• Multidirectional tuple: Is it possible to define a microservice edge between two services where the tuple would have to first go through a NORTH link, followed by a SOUTH link communication without pausing in between? It would be interesting for us.

Thank you for answering (some) of these questions, I would appreciate it!