Virtual Memory and TLBs Quiz

Questions and Answers

What is virtual memory and how does it allow programs to run when physical memory is limited?

Virtual memory is a technique used to allow programs to run when the physical memory size is smaller than the total size of all running processes. It uses main memory as a cache for secondary storage, typically a disk.

What is the purpose of a page table in virtual memory?

The page table is used to map virtual pages to physical frames or pages. It is managed by the operating system and is used to translate virtual memory addresses generated by the CPU to physical memory addresses used to access memory.

What happens when a page fault occurs in virtual memory?

When an access page is not in main memory, a page fault occurs, and the page must be retrieved from disk.

What are TLBs and how do they work?

TLBs are Translation Lookaside Buffers used to avoid virtual to physical memory address translation during cache lookup. They are organized as a cache, but each entry has a valid and a dirty bit. TLBs are often fully associative, and each entry has a tag to determine if the accessed page is present in the TLB. Signup and view all the answers

What is the typical size of a TLB?

TLBs are typically small, and the typical size is 8-1028 entries. Signup and view all the answers

What are the fields that make up a TLB entry?

TLB entries consist of several fields, including a valid bit, an RW bit, a US bit, a dirty bit, and a tag field containing the virtual page number. Signup and view all the answers

What is the purpose of the dirty bit in a TLB entry?

The dirty bit in a TLB entry indicates whether the page has been modified since it was last loaded into memory. Signup and view all the answers

How do TLBs compare the accessed page to the tags of all entries?

TLBs are often fully associative, and the tags of all entries are compared to the tag of the accessed page in parallel. Signup and view all the answers

Study Notes

Virtual Memory and Translation Lookaside Buffers (TLBs)

Virtual memory is used to allow programs to run when the physical memory size is smaller than the total size of all running processes.
Virtual memory uses main memory as a cache for secondary storage, typically a disk.
Each process has its own virtual address space, which is divided into pages.
Physical memory is divided into fixed-sized pages, and a page table is used to map virtual pages to physical frames or pages.
The page table is managed by the operating system and is used to translate virtual memory addresses generated by the CPU to physical memory addresses used to access memory.
When an access page is not in main memory, a page fault occurs, and the page must be retrieved from disk.
TLBs are used to avoid virtual to physical memory address translation during cache lookup.
TLBs are organized as a cache, but each entry has a valid and a dirty bit.
TLBs are often fully associative, and each entry has a tag to determine if the accessed page is present in the TLB.
TLBs are typically small, and the typical size is 8-1028 entries.
TLBs are often fully associative, and the tags of all entries are compared to the tag of the accessed page in parallel.
TLB entries consist of several fields, including a valid bit, an RW bit, a US bit, a dirty bit, and a tag field containing the virtual page number.