os exam revision notes

Scheduling
SJF
SRTF(preemptive SJF)
-must know burst time first
-starvation for longer process

FCFS
RR
Multi-level feedback queue

Critical Section Problem
global turn
-no progess w strict alternation

local flag
-i/o => deadlock

flag + turn
-only works for 2 process

bakery algo
-get ticket of (max + 1)
-run if no one getting ticket and <= to all

Deadlock
Mutex. Hold-Wait. No-preempt. Circular wait

Banker algo.
-needs and resources
-find exec state run all => safe state

Paging
EAT = (A + B)p + (2A + B)(1-p)
A - PT
B - TLB
p - TLB Hit %


Disk Allocation
Contig
+Random Access
-Small file

Linked
-Sequential
+Large file

Indexed
-Sequential
+large file

Max. Disk File
Inode (Add all to find max file size)
-direct = blockSize
-Single indirect = (blockSize/pter size) blockSize
-Mulitple indirect = (blockSize/pter size) (blockSize/pter size) blockSize