Report on
Operating System Support for Planetary-Scale Network Services

In this paper, Bavier et al. describe the functioning and implementation of PlanetLab.  PlanetLab is a group of computers, each running a modified linux kernel and virtual servers in which researchers can evaluate and deploy planetary scale services.  Each project is run in a slice of PlanetLab's resources which is meant to be independent of other slices that may also be using resources.  Additionally, PlanetLab nodes are decentralized from the main system and provisions must be made for the local management of the node.  The paper expands on these points and describes how they are implemented in PlanetLab's operating system.

There was a lack of basic information about PlanetLab, such as the difference between PlanetLab Central (PLC) and nodes running the PlanetLab operating system.  At times, the paper became exceedingly detailed in describing such things as the code used to bind a socket to a port.  At other times, there was such a lack of detail that the granularity used by the scheduler to provide guaranteed CPU time on nodes was not even mentioned.  The paper could have been written in a much more consistent manner.  The evaluation section of the paper left much to be desired, perhaps it could have benefited from a case study.  In general, the authors could have said more in fewer pages.

There is a strong case for the usefulness of the paper.  Almost everyone agreed that it would be helpful to users of PlanetLab.  However, the superficial nature and lack of research results called into question its validity as a research paper.  Its usefulness comes mainly from its technical description of a useful research platform, not from its own original results.  Therefore, perhaps this paper would be more appropriate as a tech report. 

Manfred Georg