###### tags: `operating system` `note` `thu`

# Chapter 6. Memory management

## 1. Virtual Memory
- Paging, 就是把Memory上對應的page對應到系統的page table上。
- 每一個Process有自己的page table, page table就是取了記憶體中的一塊區域。
- PCB上包含了page table的起始位置。

## 2. Paging Strategy
### a. Contiguous allocation
- Best fit
- First fit
- Worst fit
- 其中又有分Internal/External Fragmentation

## 3. 資料的分放
- 見Figure 9.10

## 4. Buffer
- Translation Lookaside Buffer (TLB)
- Content Addressable Memory (CAM)

## 5. Page Replacement Algorithm
- https://www.scaler.com/topics/operating-system/page-replacement-algorithm/
### a. FIFO (First In First Out)
### b. FILO (First In Last Out, stack)
### c. Optimal Page Replacement
### d. LRU(Least Recently Used)
### e. LFU(Least Frequently Used)
### f. MFU(Most Frequently Used)

## Page Fault
- Thrashing: 重複發生page fault