Xiao Liu PhD Thesis.pdf - Faculty of Information and Communication ...

makespan, the optimisation ratio on total cost, the compensation ratio on violated
workflow segment, and the CPU time of the scheduling strategy) are used here for
evaluation and comparison. Therefore, the ranking function is also designed based
on these four measurements. For fairness, the average performance on each
measurement for both GA and ACO is presented in Table 8.2.
Table 8.2 Comparison of Basic Measurements
The ranking function is defined as follows:
Rank(
OptMakespan , OptCost,
CompRatio,
CPUTime)
= w
1
OptMakespan
×
k
∑OptMakespan
i=
1
i
+ w
2
OptCost
×
k
∑OptCost
i=
1
i
+ w
Here, the weight sector { , w , w w }
3
CompRatio
×
k
∑CompRatio
i=
1
i
+ w
4
CPUTim
×
k
∑CPUTim
i=
1
w 1 2 3,
4 can be defined according to user
preference. In this chapter, since our focus is on handling temporal violations, the
compensation ratio is set with the largest weight. For instance, we set the weight
vector as {0.2, 0.2, 0.5, 0.1}. Then, according the ranking function above, the rank
values for GA and ACO are 0.575 and 0.425 respectively. Therefore, we select ACO
based rescheduling strategy, i.e. ACOWR, as the temporal violation handling
strategy in our SwinDeW-C scientific workflow system. Note that different weight
vectors may results in the selection of different strategies, but since the average
CompRatio of GA and ACO are very close, their handling capability is thus very
similar.
i
8.6 Evaluation of Three-Level Temporal Violation Handling
Strategy
The experimental results demonstrated in this section include two parts: (1) the
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