Progress Report 08/20
Virtual Core Scheduling Problem • For every time period, the hypervisor scheduler is given a set of virtual cores with their operating frequency. • Generate a scheduling plan, such that the power consumption is minimized, and the performance is guaranteed.
Current Solution • Two phases: • Use integer programming to find a feasible set of ai,j. • ai,jindicates the amount of time executing virtual core j on physical core i in a time interval. • Decide the execution order on each physical core. • A virtual core cannot appear in two or more physical core on the same time.
Execution Order • Formulate the problem into OpenShop Scheduling Problem(OSSP) with preemption.
Reduce Switching Between Cores • Migrating tasks from one core to another causes overhead. • especially migrating tasks between different core types. • Achieve better performance by reducing the total number of task switching among cores.
Example T1 : 0 T2 : 2 T3 : 1 T4 :0 T5 :0 Total: 3 T=0
Current Status • Propose a greedy heuristic last time. • Pick the “execution slice” that results in the least increment of the total switching time. • However, the result is not minimum. • Find the minimum solution by computing the switching time of all possible permutations, and compare the result with our greedy heuristic.
Something Else • Consider only the switching between different types of cores. #Switching: 6 #InterSwitching: 0 b b L L b b L L
Summary • Still working on finding the execution order that results in minimum switching time.