[LITMUS^RT] Unexpected worst case response time

[施俊杰]

Hello all,

I got some unexpected results during my experiments when using the protocol
under P-FP plugin. I used 'rtspin' to set the task, 'st-trace-schedule' to
collect the data and 'st-job-stats' to handle the data.
I set my task as follows: WCET: 1ms, critical section: 0.5 ms, partition:
cpu_0, resource location: cpu_1, protocol: DPCP, period: 2ms, total
execution time: 100s.
There is only one real-time task in my system. The result of the WCRT is
1.34 ms which is too large than the expected value. And if I set the
protocol as MPCP, partition is cpu_0 (same as resource location), the WCRT
is 1.125 ms, which is also too large.
Moreover, if I add the number of tasks to 40, the unexpected overheads of
DPCP can be accumulated to more than 1 ms.
Can any one explain that? Or do I need to modify my configuration?

Best wishes!
SHI
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