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10.8 - 10.10 ; 8.2 - Coggle Diagram
10.8 - 10.10 ; 8.2
Processes
Exceptions are the building blocks which allow processes
process is - an instance of a program in execution.
each program runs in the context of some process
Context consists of the state that the program needs to run correctly.
program's code
data stored in memory
the stack
contents of geeral purpose registers
program counter
environmental variables
set of open file descriptors
Logical Control Flow
The sequence of PC values
preempted - temporarily suspended
Concurrent flow - flow at the same time
Private address space
User and kernel Modes
Kernel mode is set with a bit
Sharing Files
How the Kernel Represents Open Files
Descriptor Table
each process has its own descriptor table. Its all the open file descriptors. Each open descriptor entry points to an entry in the file table.
File table
Shared by all processes
Contains for each entry...
current file position( a reference count of the number of descriptor entries that currently point to it.
pointer to v-node table
Closing a descriptor decrements the reference count in the associated file table entry..
The kernel wont delete the file table entry until its reference count is zero.
v-node table
Shared by all processes
Each entry contains stat structure, including st_mode and st_size members. ???