Virtual Memory and Assignment 3 Clarifications

Flashcards covering Assignment 3 updates regarding server/LLM communication and detailed exercises on multi-level page table calculations and address translation.

According to the assignment 3 update, when must the server report the port number it is listening on?

Once the server opens a listening port and before it starts the LLM.

How is an invalid HTTP request defined based on the assignment 3 function spec?

An invalid HTTP request is when the function \text{get_http_request} returns $0$.

What procedure should be followed if \text{small_lm2} disconnects or the function \text{get_http_response} fails?

The server must reestablish the connection to the LLM by establishing a new TCP connection.

In the virtual memory exercise, how many bits are in a virtual address for a system supporting process memory spaces up to $2^{23}$ terabytes?

$63$ bits (calculated as $2^{23} \times 2^{40} = 2^{63}$).

For an IA64 architecture machine using $64\text{ KB}$ pages, how many bits of the virtual address are used for the offset?

$16$ bits (calculated as $64\text{ KB} = 2^6 \times 2^{10} = 2^{16}$ bytes).

In a multi-level page table, why are the tables considered memory efficient?

Because apart from Level 1, you do not have to store the pages for memory that you are not using; you only store pages for the memory currently being used by the process.

If a virtual address maps to a page table entry with a frame number represented by a dash ( - ), what should be recorded for the physical address?

Invalid, because there is no valid physical address associated with that virtual address.

Will a segmentation fault occur if a process attempts an 'Execute' operation on a page with 'Read and Execute' permissions?

No, because the operation matches the page-level permissions.

Will a segmentation fault occur if a process attempts a 'Write' operation on a page with only 'Read' permissions?

Yes, because the process lacks the necessary write permissions for that page.

On a system with $32\text{ KB}$ pages and page table entries of $8$ bytes, how many entries are contained in a single page?

$4,096$ entries (calculated as $\frac{32 \times 1024}{8} = 4,096$).

How is the number of entries for the top level (Level 1) of a page table determined if it is a 'full table' using $12$ bits?

It is $2^{12}$ entries, which equals $4,096$ entries.

What is the assumption made when calculating memory for 'widely separated memory segments' like stack, heap, and text?

The assumption is that the segments are not sharing second-level tables.

What is the relationship between the number of offset bits in a virtual address and the size of a physical frame?

They map one-to-one, meaning the number of offset bits is determined by the size of the page or frame (e.g., $32\text{ KB}$ page = $15$ bits).

If a virtual address is $196,000$ and the page size is $64\text{ KB}$, what is the virtual page number?

Page $2$ (calculated as $\frac{196,000}{64 \times 1024} \text{ rounded down to } 2$).