CS491 ASSIGNMENT A7
due 10/21/02


We'll look this week at the principles of storage systems.
Read, in the order indicated:

1.  Before Memory was Virtual, in resources section of CS491 website.
2.  Virtual memory overview, in resources section of CS491 website.
3.  Chapter of Art of OS on storage, cne.gmu.edu/pjd/ArtOS/Storage.pdf
4.  Virtual memory section of IT core overview cne.gmu.edu/itcore

Write short answers to these questions:

(1) Mapping virtual addresses to memory addresses via a mapping
that can be dynamically altered is a central principle of virtual
memory.  How does this bring benefits for multiprogramming, overlaying,
memory partitioning, memory protection, and sharing?

(2) Suppose that memory technology continues to get cheaper.  At
some point, we will have all the computational storage we could
possibly want.  Will virtual memory continue to be useful after
this happens?

(3) The capability mapping scheme has two levels: one from user selected
strings to handles, the other from handle to descriptor.  Why does this
scheme facilitate sharing while a single-level mapping scheme does not?
Be careful: handles must have unique-in-time names (why?).  This scheme
has been resurrected in the past few years to solve the problem of
names in the Internet being reusable.

(4) Under what conditions is working-set memory management optimal?

(5) What did you learn about storage systems that you did not know
before?