A freeze/unfreeze mechanism for the LinuxThreads library

Clusters of standard components are becoming a viable alternative to traditional supercomputers. The typical architecture of these clusters is standard PCs connected by a high performance network. Another rising interest is in the use of idle computers for computation. The operating system used on this kind of platform is generally Linux because it is stable, and flexible: it can be studied, modified and tuned. When using a parallel architecture two important points are fault tolerance and load-balancing of activities scheduling. This is especially true in the context of clusters shared between users and applications and that relies on hardware not as robust as dedicated parallel machines. To provide these two services it is necessary to have a mechanism to stop, freeze, activities in a preemptive manner and, of course, one to restore them in the state they were when frozen. In this paper we present our proposal to modify the LinuxThreads library to provide this service. We do an analysis of how this library works and also give some performance results of the modified library.