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COMP 310 Operating Systems - Coggle Diagram
COMP 310 Operating Systems
Process Management
linux fork() command for child process
Multi-process system
Process scheduling
SJF (shortest job first)
RR (round robin: run each job for a fixed time)
FCFS (first come first serve)
SJF with AGING (solves starvation)
Benefit: no need to wait for I/O
Process switch
store information in PCB(process control block)
Process = code + environment
Synchronization
Process vs Thread: share space or not
Mutual Exclusion (prevent simultaneous access to a shared resource)
Lock and deadlock
Process Communication
Remote Procedure Call: call a function that belongs to the server code （不同主机之间交流）
Client and Server stubs
Message passing（同主机，不同进程之间交流）
Producer/Consumer Processes and Semaphore
Multi-threading
Critical Section: with Pthread_mutex_lock( mutex )
Variable Privatization
Data Race: unexpected access to shared data
Memory Management
Demand Paging
Transaction Look-aside Buffer (TLB): small & fast hardware cache of popular (pageno, frameno) maps. It is a part of MMU
Page: fixed-size portion of virtual memory
Frame: fixed-size portion of physical memory
Multi-level page tables
Page Replacement Policies
FIFO
OPT (imaginary)
Random
LRU (least recently used)
Virtual Memory
MMU provides mapping virtual-to-physical
Memory Management Unit (MMU)
MMU provides protection so that one process cannot access another process's memory
mapping schemes
Segmentation
Paging
Base and bounds
File System Management
Data allocation strategies
Linked data blocks
Indexed nodes (direct pointers, indirect pointers, double indirect pointers....)
Contiguous data blocks
FAT (file allocation tables)
LSF: log-structured file system
A way to implement atomicity
Imap: inode map
Use checkpoint to boost recovery
Disk scheduling
C-LOOK
SSTF
C-SCAN（只在向下扫描时沿途执行，然后把针头调到顶，重新向下扫描）
SCAN（向下扫描时沿途执行，向上时也沿途执行）
RAID: redundant array of independent disks
Optimize I/O bandwidth through parallel I/O
Recovery using the parity function
Analyze capacity, latency, throughput
Hard link & Soft link