All language subtitles for 5_Memory Management and Virtual Memory

Remember that when a process runs, it
needs CPU time, but it also needs memory.

When processes are run,
they have to take up space in memory, so

that the computer can read and
load them quickly.

However, compared to our hard disk drives,
memory comes in smaller quantities.

So to give us more memory
than we physically have,

we use something called virtual memory.

Virtual memory is the combination
of hard drive space and

RAM that acts like memory
that our processes can use.

When we execute a process,

we take the data of the program
in chunks we call pages.

We store these pages in virtual memory.

If we want to read and
execute these pages,

they have to be sent to physical memory or
RAM.

Why don't we just store the entire program
in RAM so we can execute it quickly?

Well you could,
if it was small enough, but for

large applications it would be wasteful.

Have you ever worked in a word processor
and then gone to a menu don't normally use

and noticed the application
slow down a little?

It's because your computer
had to load the page for

that menu from virtual memory into RAM.

We don't use all the features
of our application at once.

So why load it up at once?

It's similar to cooking
a recipe from a cookbook.

You don't need to read the whole
book just to make one recipe.

You only need to read the pages of
the recipe you're currently using.

When we store our virtual
memory on our hard drive,

we call the allocated space swap space.

When we get into practical
applications of disk partitioning,

we'll allocate space for swap.

The kernel takes care of all of this for
us of course.

It handles the process of taking pages of
data and swapping them between RAM and

virtual memory.

But, the kernel isn't
the only hard worker around.

You've done great getting
through the lessons so far.

Nice work.