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Distributed operating systemsThe method works best with small groups of processes that never change their group memberships. Finally, recall that one of the problems with the centralized algorithm is that making it handle all requests can lead to a bottleneck. In the distributed algorithm, all processes are involved in all decisions concerning entry into critical regions. If one process is unable to handle the load, it is unlikely that forcing everyone to do exactly the same thing in parallel is going to help much. Various minor improvements are possible to this algorithm. For example, getting permission from everyone to enter a critical region is really overkill. All that is needed is a method to prevent two processes from entering the critical region at the same time. The algorithm can be modified to allow a process to enter a critical region when it has collected permission from a simple majority of the other processes, rather than from all of them. Of course, in this variation, after a process has granted permission to one process to enter a critical region, it cannot grant the same permission to another process until the first one has released that permission ...» |
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