Lecture Topic: Processes
Parts of memory
- Stack
- Heap
- Program Counter
- Registers
- Arguments Vector
- Environment PATH

| Stack Layout                   |
| ------------------------------ |
| argv, argc                     |
| stack                          |
| heap                           |
| uninitialized global variables |
| initialized global variables   |
| text                               |

Heap Memory, only the result of calls to malloc or calloc
Stack Memory, anything else, even pointers or custom typedefs, unless it was specifically allocated

Possible Process States
- New: First Stage, when the OS loads the program and before it is given CPU cycles
- Ready: When the program is ready to execute and has been added to the OS queue for execution
- Running:  The program is executing instructions on the CPU
- Waiting: The program is waiting for CPU cycles or is dormant, either due to timeout or waiting for IO or events
- Terminated: The program memory is unallocated and revoked. Can be invoked by program itself or by parent (includes OS)

Process Control Block or Task Control Block
- Process state
- Program counter
- Scheduling information
- Memory info
- Accounting info
- IO status info (fds, etc)
In Linux this is implemented with a structure called `task_struct`

It's organized in a Linked List, it's used for scheduling.

The process scheduler, selects which process get CPU attention, with the goal of improving response time, as well as multiprorgramming.

Maintained Queues
- Waiting Queue
- Ready Queue

Processes could be CPU bound or IO bound

In general 100% utilization (CPU, IO) is not bad