Transparent Energy Accounting in Distributed Systems

Torsten Ehlers

Advisor: Andreas Weißel, Dr.-Ing. F. Bellosa

Registered as Studienarbeit SA-I4-2004-09 , March 1 2004

[Abstract] [Full Paper (pdf) , 288 kB]

Power consumption is a crucial characteristic of modern hardware, both for mobile, battery-driven devices and for high-end servers. Servers are increasingly highlyintegrated in modern data centers and the power density per unit area is rising. This also induces higher heat densities. Costs for electricity supply and for necessary cooling equipment are not insignificant anymore. Higher clock speeds and growing demand for always-on services will intensify this problem even more. Methods to account and limit power consumption on the application- or task-level for standalone hosts have been successfully adopted. However, those methods lack support for distributed systems.

This thesis introduces a transparent energy accounting scheme for distributed systems. The well-known abstraction of resource containers representing resource principals in a system is extended to global resource containers to allow accounting of energy dissipation across system boundaries. With this extension, energy consumed for the accomplishment of a certain task within a server cluster can be accounted to a resource container globally. When a server is working on behalf of a client, the server is bound to that client’s resource container only until its work for this client is completed. Server and client processes do not have to reside on the same host for this scheme. Information is sent piggyback with normal IPv6 network traffic, transparently for the applications. This way it is possible to accurately account energy consumption to its originator, even if this originator does not exist on the same host. Limiting global resource containers and using them for priority models or thermal management of computer clusters is achievable as well and presented in this work.

As a prototype implementation a modified Linux kernel running on Intel Pentium 4 CPUs is presented and tested with several experiments that prove its effectiveness.