Linux

Linux

1. Memory Management

   • Swapping vs paging
   • Kernel, memory map,page frames
   • Text, data, stack segments

2. Process: instance of a program

   • Thread: path through process. Can share file descriptors
     • Task: lowest unit of execution
     • Task struct
   • Process Scheduler: CFS, threads -> CPUS
     • Fork: copy on read
     • Syscalls: user space to kernel space via trap
       • Cross-call: CPU request other CPU
       • System library
     • Runque: expired <-> active lists
   • Signals
     • Zombie: until parent waits for it
     • Pause: suspend until sigalrm
   • Pipe: inter-process channel. Take MVar
   • Daemon: background process
   • Context-switch: store process state

3. I/O

   • Block-device driver: random access e.g. disk
   • Character-device driver: stream input e.g. keyboard
   • Interrupt: signal sent, device -> kernel. Has priority
     • 1) ASAP 2) Scheduled later
   • VFS: integrates all I/O

4. General

   • Kernel: program to manage system, runs in CPU mode allowing direct access to hardware
   • Shell: program. First word -> program
     • Fork -> Exec -> WaitPID
   • Filesystem
     • Etc: system cofnig, usr: user programs, dev: device, var: variable files, tmp, home, bin: binary exe
     • Lock: manage concurrent file access. Shared vs exclusive
     • Dentry cache: store dir entries