[aadl-modeling]: Port connections and latency analysis

[Peter Feiler]

Hi,

Have you checked out the documentation in the online help of OSATE under OSATE Core Documentation Analyses?

When you say cyclical messages do you mean sampled processing?
You can attach the period property to your leaf component – it does not have to be a thread
From the documentation:
Sampling Delay in Periodic Sampled Processing
In embedded systems it is common to perform periodic sampled processing. Examples are displays refreshing at a specified rate, sensors sampling the physical environment at a given rate, application systems processing their input periodically (periodic threads). This can result in a sampling delay as latency contribution, i.e., the amount of time incoming data is in the incoming port until the component is dispatched.
The Period property allows users to specify the time interval at which a component executes. We can annotate a system, abstract, process, thread group, thread, device component with a period.
You mention defining flows and binding flows to buses. Flows in AADL are specification of flows from input to output within a component. This allows us to calculate latency without having to have an implementation for the component. You have connections from the output of one component to the input of another component. You can associate a latency value with the connection. You can also bind the connection to a bus used as transport mechanism – you can also use virtual buses to represent protocols with their latency contributors.
The latency analysis uses information from the bound bus – if not present it uses the latency associated with the connection itself.

In AADL you specify your functional or task and communication architecture separate from the platform, e.g., connections between threads (via their enclosing components such as process or system). Binding of threads to processor determines who executes where and connections to buses and other HW component to indicate the hardware involved in the communication.

Peter


From: aadl-modeling-bounces+phf=sei.cmu.edu at lists.sei.cmu.edu [mailto:aadl-modeling-bounces+phf=sei.cmu.edu at lists.sei.cmu.edu] On Behalf Of David K
Sent: Wednesday, May 2, 2018 11:45 AM
To: AADL Modeling <aadl-modeling at lists.sei.cmu.edu>
Subject: [aadl-modeling]: Port connections and latency analysis

Good afternoon,

I modelled a AADL-system containing several subsystems connected via busses. Now I want to do a basic latency analysis of the systems communicating via cyclical messages but I don't know how to do it.


My approach is:
1. defining the ports of the subsystems
2. define the flows with their latency times
3. define the bus properties
4. binding the flows to a bus


The cyclical part is still missing in my approach. Do I need to implement the threads of the subsystems as well for this?
And if I need to implement the threads: Are the data flows directly connected from the thread-ports to the system-ports or are they going through the processor?


Kind regards
David
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