2.3 ELST (Effective Least Slack Time First) Preemptive LST is an optimal algorithm in real-time scheduling algorithm. However, in CPS, we need to consider physical environments to improve deadline meet ratio. As an example, we have to consider moving time of computing (servicing) node to the location of task serviced. Let’s denote leff, be an effective slack time of task i (slack time including moving time), then is computed as i leff, i following: = leff, i li - mi. (7) Now, we compute the As distribution of is (when > 0) distribution is leff, i. l i leff, i leff, i λ, computed as follow: (8) (when < <0) distribution is computed as follow: leff, i leff, i –M (9) An average deadline meet ratio of task A (without conflict) is the probability of > 0. leff, i (10) Deadline meet ratio of task B following task A is: (11) As we assume and are evenly distributed on [0, M] and [0, E], respectively, mean (DMB (λ, mA eA is computed as: mA, eA, mB))
2.3 ELST (Effective Least Slack Time First) Preemptive LST is an optimal algorithm in real-time scheduling algorithm. However, in CPS, we need to consider physical environments to improve deadline meet ratio. As an example, we have to consider moving time of computing (servicing) node to the location of task serviced. Let’s denote leff, i be an effective slack time of task i (slack time including moving time), then leff, i is computed as following: leff, i = li - mi. (7) Now, we compute the leff, i. As distribution of l i is λ, leff, i (when leff, i > 0) distribution is computed as follow: (8) leff, i (when –M < leff, i <0) distribution is computed as follow: (9) An average deadline meet ratio of task A (without conflict) is the probability of leff, i > 0. (10) Deadline meet ratio of task B following task A is: (11) As we assume mA and eA are evenly distributed on [0, M] and [0, E], respectively, mean (DMB (λ, mA, eA, mB)) is computed as:
Effective%20Real-Time%20Scheduling%20Algorithm%20for%20Cyber%20Physical%20Systems%20-%2020130828-%203rd%20rev..docx