CSC369H1 Study Guide - Midterm Guide: Doubly Linked List, Interrupt, System Call
8 Apr 2015
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In one sentence, explain why. (if you disagree that the statement is false, provide your reasoning. ) [1 mark] a system call is invoked in the same manner as a user function. A system call traps into the kernel so that priviliged instructions can be run. A function call just jumps to another instruction in user-mode. (might say, switch to kernel-mode, software interrupt, syscall instruction. ) [1 mark] malloc and free must maintain data structures that track all free and allocated. It isn"t neccessary to keep a list of allocated blocks, since there is no reason to traverse them. It is up to the user-level program to keep track of allocated pointers so that memory isn"t lost . (i could imagine an argument that leads toward gc, but that isn"t really the point here. ) [1 mark] if two threads access a shared variable at the same time, there will be a concurrency.
