1
Q
I/O 3 Facts
A
- Have protocols
- Have dedicated handlers
- Decouple I/O details from core processing
2
Q
Microcontroller
A
Device’s CPU
3
Q
Command Registers
A
- Command
- Data transfers
- Status
4
Q
PCI
A
Peripheral Component Interconnect
5
Q
Character device
A
get/put character
6
Q
BAR
A
Base Address Registers
7
Q
Memory Mapped IO
A
Part of host physical memory dedicated for device interactions
8
Q
IO Port Model
A
Dedicated in/out instructions fro device access
9
Q
PIO
A
Programmed I/O
- No additional hw support needed
- CPU programs device via command registers
10
Q
DMA
A
Direct Memory Access
- 2 CPU instructions, but 1 is complex
- Data must be in physical memory (Pinned)
11
Q
Typical Device Access
A
- system call
- in-kernel stack
- driver invocation
- device request configuration
- device performs request
12
Q
indoe
A
persistent representation of file “index”
list of all data blocks
13
Q
dentry
A
directory entry
14
Q
superblock
A
filesystem-specific information regarding the FS layout
15
Q
superblock contents
A
inode blocks
data blocks
free blocks
16
Q
Direct Access Optimizations
A
Caching/Buffering
I/O Scheduling
Prefetching
Journaling/Logging
