[LITMUS^RT] Feather Trace Deadline Misses

[De Bock Yorick]

Dear,

I'm using Litmus-RT for my PhD project to test the schedulability of real-time tasks.

I use base_task as starting point to create real-time tasks and the execution time approaches the wanted execution time.

Now I'm testing at which task-set utilization deadline misses start to occur. To trace this I use Feather Trace.

As long as I don't have any deadline misses I can trace every job of each task perfectly. But if I have deadline misses the traces shows a gap (output0: line 2571-2620) where only the release events are recorded (no completion, switch_to and swtich_away events). For each task a couple jobs has no tracing information, and this increase if the utilization increases.

I attached the .bin file, and the converted files to human readable format.

My question is if this the normal behaviour of feather trace/litmus-rt. Because I aspect to have deadline misses at this utilization, but I need to know at what exact moment the deadline misses happen.

Set-up: Intel(R) Xeon(R) CPU E5-2420 v2 @ 2.20GHz, RT-XEN, VM with 1 VCPU which can use 1 CPU 100% (budget == period), scheduler: GSN-EDF
TaskSet utilization: ~94-95 % (measured execution time of all jobs/(time of latest completion - time of first release)).

Thanks in advance.

Ing. Yorick De Bock
PhD Student

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