Paging

Filtering, Sorting, and Paging

Building efficient, parameterized queries with Where, OrderBy, and Skip/Take, plus the tradeoffs of offset versus keyset pagination.

Demand Paging

Lazy loading of pages into memory only when referenced, and the step-by-step page-fault handling sequence that makes it work.

Paging

Splitting logical and physical memory into fixed-size pages and frames to eliminate external fragmentation.

Difference Between Paging and Segmentation

Paging divides memory into fixed-size blocks called pages (mapped to equal-size frames in physical memory), while segmentation divides memory into variable-siz…

What is Virtual Memory?

Virtual memory is a technique that gives each process the illusion of a large, private, contiguous address space by mapping virtual addresses to physical RAM (…

What is Thrashing in Operating Systems?

Thrashing is a state where a system spends most of its time swapping pages between RAM and disk rather than executing actual instructions, causing CPU utilizat…

What is Demand Paging?

Demand paging is a virtual memory technique where a page is loaded into physical memory only when a process actually references it, rather than loading the who…

What Is Fragmentation?

Fragmentation is the wasted memory that builds up as blocks are allocated and freed over time, leaving usable space scattered in pieces too small or too oddly…

What is the FIFO Page Replacement Algorithm?

First-In-First-Out (FIFO) page replacement evicts the page that has been resident in memory the longest, regardless of how recently or frequently it has actual…

What is the LFU Page Replacement Algorithm?

Least Frequently Used (LFU) page replacement evicts the page with the smallest access count, on the assumption that pages referenced rarely overall are less va…

What is Segmentation with Paging?

Segmentation with paging is a hybrid memory management scheme where a process's address space is first divided into logically meaningful, variable-sized segmen…

Internal vs External Fragmentation

Internal fragmentation is wasted space inside an allocated block because it is larger than what was requested, while external fragmentation is wasted space bet…

What is Contiguous Memory Allocation?

Contiguous memory allocation is a memory management scheme where each process is assigned a single unbroken block of physical memory addresses, with the OS tra…

What is the Dirty Bit in Paging?

The dirty bit (also called the modified bit) is a single flag in each page table entry that the hardware sets whenever a process writes to that page in memory,…

What is the Reference Bit in Paging?

The reference bit (also called the accessed bit) is a single flag in each page table entry that the hardware sets whenever a page is read or written, giving th…

What is Pure Demand Paging?

Pure demand paging is a memory management policy where absolutely no page of a process is loaded into RAM until the process actually references it, so every pr…

What is Prepaging?

Prepaging is a memory management optimization where the OS loads a batch of pages it predicts a process will need into RAM before they are actually referenced,…

What are the Tradeoffs of Page Size?

Choosing a larger page size reduces page table size and TLB pressure and improves transfer efficiency for large sequential reads, while choosing a smaller page…

What are Memory Protection Mechanisms?

Memory protection mechanisms are hardware- and OS-enforced controls -- base/limit registers, per-page permission bits, and separate virtual address spaces -- t…

What is the Overlay Technique in Memory Management?

The overlay technique is a memory management method that lets a program larger than available physical memory run by keeping only the currently needed portion…

What is Relocation in Memory Management?

Relocation is the process of adjusting a program’s memory address references so it can be loaded and correctly executed at a physical memory location that is d…

What Causes External Fragmentation and How Is It Solved?

External fragmentation happens when free memory becomes scattered into many small, non-contiguous holes so that even though total free space is sufficient, no…

What Is the Medium-Term Scheduler and How Does Swapping Work?

The medium-term scheduler temporarily removes a process from memory (swaps it out to disk) to reduce the degree of multiprogramming, then later swaps it back i…