  It is common for cloud data centers meeting unexpected loads like request
bursts, which may lead to overloaded situation and performance degradation.
Dynamic Voltage Frequency Scaling and VM consolidation have been proved
effective to manage overloads. However, they cannot function when the whole
data center is overloaded. Brownout provides a promising direction to avoid
overloads through configuring applications to temporarily degrade user
experience. Additionally, brownout can also be applied to reduce data center
energy consumption. As a complementary option for Dynamic Voltage Frequency
Scaling and VM consolidation, our combined brownout approach reduces energy
consumption through selectively and dynamically deactivating application
optional components, which can also be applied to self-contained microservices.
The results show that our approach can save more than 20% energy consumption
and there are trade-offs between energy saving and discount offered to users.
