×10^6
1.41.01.20.8
0.6
0.4
0.2Time (s)User bid ($)0.310 0.315 0.320 0.325 0.330 0.335 0.340(a) Total task execution timeUser bid ($)0.310 0.315 0.320 0.325 0.330 0.335 0.340252015Costs ($)Lower BBMiddle BB
Upper BBEIC(b) Total costsFigure 18: Comparison of actual EIC outputs (execution time and
cost) and estimations according to the user bid.
×10^5Time (s)HBC
REC
EIC2.5
2.0
1.5
1.0
0.5
0.043,^200
86,^400
129,^600
172,^800
216,^000
259,^200
302,^400
345,^600Task time (s)Figure 19: Comparison of rollback times according to the task time.
Table 3: Simulation parameters and values.Parameter Value
User bid $0.32
Checkpoint time 300 sec
Recovery time 300 sec
Minimum task time 43,200 sec
Maximum task time 345,600 sec
Task time interval 43,200 seclessens the rollback time on average by 80.61% and 84.36%
over HBC and REC, respectively.
Figure 20shows the performance comparison of EIC,
HBC, and REC. Figures20(a)and20(b)show the numbers
of failures and checkpoints, and total task execution time and
total failure time according to the task time. The EIC reduces
the number of checkpoints on average by 31.97% and 32.93%
43,^200
86,^400
129,^600
172,^800
216,^000
259,^200
302,^400
345,^600Task time (s)Event count numberFailure count (HBC)
Failure count (REC)
Failure count (EIC)Ckp count (HBC)
Ckp count (REC)
Ckp count (EIC)200
175
150
125
100
75
50
25
0(a) Number of failures and checkpoints43,^200
86,^400
129,^600
172,^800
216,^000
259,^200
302,^400
345,^600Task time (s)
Total time (HBC)
Total time (REC)
Total time (EIC)Total failure time (HBC)
Total failure time (REC)
Total failure time (EIC)×10^6Time (s)1.8
1.5
1.2
0.9
0.6
0.3
0.0(b) Total task execution time and total failure timeFigure 20: Performance comparison according to the task time.Costs ($)Total price (HBC)
Total price (REC)
Total price (EIC)Task time (s)60
50
40
30
20
10
043.20086.400129.600172.800216.000259.200302.400345.600Figure 21: Comparison of total costs.compared to HBC and REC, respectively. Thus, the EIC
achieves performance improvements in the task execution
time on average by 43.79% and 48.25% over HBC and REC,
respectively.
Figure 21showsthetotalcostaccordingtothetasktime.
The EIC reduces the cost on average by 39.38% and 40.08%
compared to HBC and REC, respectively.
Figure 22shows the combined performance metric, the
product of the total task execution time, and cost. The rate of
increase in the product in EIC is lowest among the compared
schemes. The EIC achieves a performance improvement on