User process, kernel
to make a system call an application must
– write argoments
– save relevant data at well-defined location
– make system call
User/Kernel Transitions
・hardware supported
e.g. traps on illegal instructions or memory accesses requiring special privilege
・involves a number of insturctions
e.g. -50-100ns on a 2GHz machine running Linux
・switches locality
-> affects hardware cache
・process management
・file management
・device management
kill
setgid
mount
sysctl
monolithic OS
+everthing included, inlining, compile time optimizations
-customization, portability, manageability, momory footprint, performance
module OS
-operating system, module(Interface)
Microkernel
operating system, address space, threads
Linux architecture
Hardware(cpu, memory, disks, terminal), Linux operating system(process management, memory management, the file system;I/O, etc), standard library(open, close, read, write, fork, etc), standards utility programs(shell, editor, compilers, etc), users
