abstract = "Data centres are one of the most power hungry sections
of the Information and Communications Technologies
(ICT) sector. In the U.S in 2014, data centres consumed
around the 1.8percent of the total U.S electricity
consumption. Worldwide data centers consumed in 2015
around 200 TWh of the global electricity usage. This
electricity consumption is expected to increase to
around 1200 TWh in 2025, which would represent
4.5percent of the global electricity usage. One of the
major contributors to the overall data centre power is
the IT or computing power, therefore there is a special
interest to improve its energy efficiency. Scientific
community has developed energy efficient techniques to
reduce the energy consumption of IT equipment, such as
resource management, power budgeting or power capping.
These techniques assume the existence of a full dynamic
power profiling, obtained through a previous full
execution of the application. This full dynamic
profiling is not viable in scenarios of long-running
applications that are deployed in data centers, since
performing a full dynamic profiling of a large batch of
long-running applications is a time consuming process
thus not energy-efficient. Therefore, we propose the
use of an application signature to estimate the energy
in a fast way without the need to execute the
application from beginning to end. The application
signature is a reduced version, in terms of execution
time, of the original application. We developed a fast
energy estimation framework that uses the application
signature to make a quick energy estimation of
long-running applications. The framework estimates,
without performing a full profile of the application,
the dynamic CPU and memory energy of both
single-threaded and multi-threaded long-running
application versions. Additionally, the fast energy
framework is automatic and it has a modular design,
allowing to change the functionality of each module
without altering the functionality of the whole
framework. We validated the accuracy of the fast energy
estimation framework with a set of sequential and
multi-threaded long-running applications. For the
single-threaded version of the applications we obtained
an RMS of 10.4percent for the CPU energy estimation
error and an RMS of 16.8percent for the memory energy
estimation error. In the multi-threaded scenario, we
used a subset of applications from the sequential
version set. We achieved an RMS of 11.4percent for the
CPU energy estimation error and an RMS of 12.8percent
for the memory energy estimation error. We defined the
concept of Compression Ratio (CR) as the ratio of total
execution time of the original application, to the time
it takes to estimate the energy through the fast energy
estimation framework. A high CR value indicates that
the energy is estimated much faster (CR times faster)
than executing the whole application. We obtained
Compression Ratios in the range from 10.1 to 191.2.
Finally, we validated the usefulness of the energy
estimation obtained from the application signature by
applying three different energy-efficient task
scheduling approaches: i) An optimal approach using a
Mixed Integer Linear Programming (MILP) technique, ii)
An energy-aware heuristic approach that uses a Longest
Task First (LTF) algorithm together with an
energy-efficient task allocation based on the current
servers consumption, and iii) We proposed an
implementation of a metaheuristic using a Simulated
Annealing process. The results obtained through the
energy estimation (obtained through the application
signature) values are compared with the real energy
values. We obtained energy savings from 8percent to
19percent, and more importantly the energy savings
obtained with the application signature approach are
similar to the values obtained with the real energy
measurements, with an energy savings difference below
1.5percent",
notes = "GE (Appendix A) used 'to develop the power (Section
4.2.1.1.2) and co-allocated hardware counters (Section
4.2.2) models'
Supervised by: Jose Luis Ayala Rodrigo and Marina
Zapater Sancho and Jose Manuel Moya Fernandez",