HDSA（hybrid dynamic scheduling algorithm） was proposeed

which slows down processor via voltage/frequency scaling

such that the real-time schedulability and task synchronization can be satisfied concurrently with as minimum as possible energy consumption.Based on RM and EDF

HDSA consists of a static algorithm and a dynamic one.The static algorithm computes the initially static speeds of all tasks under the static conditions.The dynamic algorithm fixes the execution frequencies of all critical sections at runtime

and reclaims the slack of tasks during their executions so as to further reduce energy consumption while satisfying timing constraints.On the other hand

frequent voltage switching

which is caused by the frequency inheritance

can be avoided by the approach when a task with a lower priority blocks a task with a higher priority.Consequently

the scheduling costs can also be reduced efficiently.The experimental results illustrate that the proposed algorithm obviously outperforms existing algorithms in terms of energy consumption.