Preemptive scheduling entails some extra scheduling overhead compared to non-preemptive.

Preemptive scheduling gives all processes a chance to run every so often, which improves.

As described in class, strict alternation causes one thread to block indefinitely while waiting to enter the critical section if the other thread never takes its turn. This violates one of the requirements for a correct implementation of critical sections.

An effective way to prevent deadlock is for the OS to require every process to request all of the resources (locks, files, etc.) when it begins to execute, and then release them all when it completes. prevention that eliminates one of the necessary.