About Execution time for real time tasks

Hello,

I was using the Embedded Coder to generate the code and run it on QEMU Arm Cortext-A target hardware emulator. The approach used was Professor In the Loop (PIL) simulation. I configured the setups using this target hardware and generated the C code and deployed into the emulator. Then I inspected the running time. But I couldn't figure out why every time the running time for the tasks are much higher at the beginning of the simulation time, even though the task itself is a very simple one. Here are some of the screenshots I got:

This figure shows the report, see the subsystem step (the task) max running time is 8e-5 seconds, average time is 3.3e-5 seconds.

This figure shows the timeseries data for the running time of that task, see the 8e-5 seconds running time happens at the beginning.

This is the algorithm for the task, see it is very simple, just output = input * 2.

This is the top model, see even for the input for each time step I set it as a constant 1.

The hardware target I used for the Embedded Coder is Arm Cortest-A.

So, I really don't know why it has various running times for such a simple task with constant inputs, especially at the beginning with such a huge running time.

Can someone please help me?

Thanks