On-Line Real-Time Service-Oriented Task Scheduling Using TUF

Algorithm 3

Preemption checking.

1: input: Let 𝜏₀ be the task currently being executed, and

 𝜏_𝑝 be the task wants to preempt 𝜏₀, current time be 𝑡,

 𝜌₀(𝜏₀,𝑡) be the conditional expected utility density of 𝜏₀

 at time 𝑡, 𝜌_𝑝(𝐶_𝑝) be the expected utility density of 𝜏_𝑝,

 𝐶_𝑝 and 𝐶₀ are the expected execution time of 𝜏_𝑝 and 𝜏₀,

respectively;

2:

3:When a new task arrives or it is the preemption checking

 point

4: If 𝜌_𝑝(𝐶_𝑝)−𝜌₀(𝜏₀,𝑡)>𝜁 then

5:  Check what is 𝜏₀’s worst case finish time;

6:  If 𝑆_𝜏0+𝑊𝐸_𝜏0≤𝐷_𝜏0 then

7:   Preemption not allowed;

8:  else

9:   Preemption allowed;

10:  end if

11: end if