Operating System Kernel Design

Memory Management

Each process has one virtual address space, with addresses running from zero to some huge maximum. Virtual memory is divided into pages, usually of 4 kilobytes in size. Paging is the process of managing the virtual memory to real memory translations.

A process' virtual address space is divided into segments. A segment is a contiguous range of virtual addresses. Three important segments are:

• text segment contains a program's instructions
• data segment is working storage for the program.
• stack segment contains a program stack. It grows as the stack grows, but doesn't shrink when the stack shrinks.

Module 3

vim process.c

main()

{

int j=0;

int k;

int *ptr;

ptr=(int *)malloc(70000*sizeof(int));

while(1)

{

j++;

if(j=100)

j=0;

}

}

cat /proc/5767/maps

The first two regions refer to the code and data and then we have heap region. After we have regions based on standard C library which is specified by the files in /lib. After that we have stack segment and segments which is used for system calls.