  Serverless workflows have emerged in FaaS platforms to represent the
operational structure of traditional applications. With latency propagation
effects becoming increasingly prominent, step-wise resource tuning is required
to address the end-to-end Quality-of-Service (QoS) requirements. Modern
processors' allowance for fine-grained Dynamic Voltage and Frequency Scaling
(DVFS), coupled with the intermittent nature of serverless workflows presents a
unique opportunity to reduce power while meeting QoS.
  In this paper, we introduce a QoS-aware DVFS framework for serverless
workflows. {\Omega}kypous regulates the end-to-end latency of serverless
workflows by supplying the system with the Core/Uncore frequency combination
that minimizes power consumption. With Uncore DVFS enriching the efficient
power configurations space, we devise a grey-box model that accurately projects
functions' execution latency and power, to the applied Core and Uncore
frequency combination. To the best of our knowledge, {\Omega}kypous is the
first work that leverages Core and Uncore DVFS as an integral part of
serverless workflows. Our evaluation on the analyzed Azure Trace, against
state-of-the-art (SotA) power managers, demonstrates a power consumption
reduction of 20\% while minimizing QoS violations.
