CODEWITHSUNDEEP
crtospriority-inversion
Giuseppe Denina Rivera
Giuseppe Denina Rivera

Reputation: 11

OSEK, shared resource and priority inversion

I'm encountering an issue with 3 tasks running on SimulIDE. 2 of them share the same resource. A has priority higher than C (they 2 share the resource), but as soon as C requests the resource, it somehoiw gets preempted by task A while in its critical section.


I'm using a timer: 
void do_things(int ms=1){
    unsigned long mul = ms * 504UL;
    unsigned long i;
    for(i=0; i<mul; i++) {
        millis();
    };

to simulate busy cycles.

I tried changing tick times and changing the order of functions in the code but here's the result:

[taskC_1]
C start: 2799-->
start_do_things_100
end_do_things_100
C:Resource Requested at: 2900
start_do_things_200
end_do_things_200
[taskA_3]
A start: 3102-->
A:Resource Requested at: 3102
A:Resource Released at: 3303
A end:--> 3304


[taskB_2]
B start: 3304-->

[taskA_4]
A start: 3997-->
A:Resource Requested at: 3997
A:Resource Released at: 4198
A end:--> 4199

B end:--> 4208

C:Resource Released at: 4208
C end:--> 4209

as you see, A starts after C has taken the resource

Upvotes: 1

Views: 11

Answers (0)

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