Critical-Section
system of n processes {p0, p1, … pn-1}
1 Each process has critical section segment of code
-Process may be changing common variables, updating table, writing file, etc
-When one process in critical section, no other may be in its critical section
2 Critical section problem is to design protocol to solve this
4 Each process must ask permission to enter critical section in entry section, may follow critical section with exit section, then remainder section
4 Especially challenging with preemptive kernels