Explain the advantage of copy-on-write region copying for UNIX, where a call to fork is typically followed by a call to exec. What should happen if a region that has been copied using copy-on- write is itself copied?
What will be an ideal response?
It would be wasteful to copy the forked process’s address space contents, since they are immediately replaced. With copy-on-write, only those few pages that are actually needed before calling exec will be copied.
Assume now that exec is not called. When a process forks, its child may in turn fork a child. Call these the parent, child and grandchild. Pages in the grandchild are logically copied from the child, whose pages are in turn logically copied from the parent. Initially, the grandchild’s pages may share a frame with the parent’s page. If, say, the child modifies a page, however, then the grandchild’s page must be made to share the child’s frame. A way must be found to manage chains of page dependencies, which have to be altered when pages are modified.
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An animation that has been set to ____ will play continuously.
A. Build B. Looping C. Once D. Chain
Once the changes are recorded, you can review the shared file and decide to ________
A) accept or reject the changes B) delete the file C) refresh the changes D) discard the file
The ability to run more than one program at once is called multitasking
Indicate whether the statement is true or false
When a user is created with a blank password and the password policy requires a non-blank password, you will not be able to create the user or you must change the policy.
a. true b. false