Introduction #

Once a system is multitasking and supports multiple users, a new problem appears.
There are limited resources, but many programs want to use them at the same time.

The two most important questions the operating system must answer are:

• Who gets the CPU now?
• Who has to wait?

This is where scheduling and resource management come in.

What Scheduling Means #

Scheduling is about deciding which process runs on the CPU and when.

The CPU can execute only one process at a time.
But the system may have:

• Dozens of running programs
• Background services
• System tasks

The operating system keeps track of all these processes and decides:

• Which process should run next
• How long it should run
• When it should be paused

This decision happens continuously while the system is running.

Why Scheduling Is Needed #

Without scheduling:

• One process could take the CPU forever
• Other programs would never run
• The system would appear frozen

Scheduling ensures:

• Fair use of the CPU
• No single process blocks others
• Important tasks get CPU time when needed

This is why even simple systems need a scheduler.

Time Sharing in Simple Terms #

The OS uses time sharing to manage the CPU.

It gives each process a small slice of CPU time.
When the time slice ends:

• The current process is paused
• Its state is saved
• Another process is given the CPU

This happens very fast, so users feel everything is running together.

What Resource Management Means #

CPU is not the only resource.

The operating system also manages:

• Memory
• Storage
• Input/output devices
• Network access

All of these are shared resources.

If they are not managed properly:

• Memory can be exhausted
• Devices can be locked
• Programs can interfere with each other

Resource management is about controlled sharing.

How the OS Manages Resources #

The operating system:

• Tracks which process is using which resource
• Grants access when available
• Denies or delays access when busy
• Reclaims resources when a process finishes

For example:

• Memory allocated to a process is freed when it exits
• A file is unlocked when it is closed
• CPU time is redistributed continuously

Applications do not handle this themselves.
The OS does it for everyone.

Scheduling and Resource Management Work Together #

Scheduling and resource management are closely related.

A process may:

• Be ready to run but waiting for CPU
• Be paused because it is waiting for I/O
• Be blocked because memory is not available

The OS constantly checks these conditions and makes decisions.

This coordination is what keeps the system responsive and stable.

Why This Matters in Linux #

Linux systems often run:

• Many background services
• User applications
• Network processes

Good scheduling ensures:

• Interactive programs stay responsive
• Background tasks do not take over the system
• Servers can handle many users smoothly

Poor scheduling or resource handling would make Linux unreliable.

Summary #

Scheduling decides:

• Which process runs on the CPU
• When it runs
• How long it runs

Resource management ensures:

• Fair sharing of CPU, memory, and devices
• Protection between processes
• Stable system behavior

Both are core responsibilities of an operating system.
Without them, multitasking and multi-user systems would not work.