In the last article, we asked ourselves how the operating system gives each process the illusion that it has its own address space despite only having one hardware RAM. This is one of the most important and most complicated virtualization techniques that the operating system performs.

I ran into an article in the Linux Weekly newsletter that talked about BPF and got curious what it was. BPF (also known as Berkeley Packet Filtering) is a technology that serves as a “faster” alternative to interacting with kernel-space from user-space. Woah, that’s nuts; I didn’t even know such a thing existed!

The first operating system was almost like a computer at a modern day library. Nobody owns it, and if you wanted to use it, you may need to book some time out with a librarian. You may have an hour to use the computer, but you’ll spend at least 10 - 15 minutes getting set up: downloading applications you need, loading files, logging in to websites. It may not seem like much but the overhead definitely adds up. Operating systems in the 1950s were very similar, you would have to book some time out with a human operator and they would schedule a slot for you to run your job. It would take you a while to set up your program, but once you had, you were free to run it for the remainder of your slot.

Have you ever wondered how your 6-core MacBook is able to run more than 6 programs at once? Each core is executing one instruction at a time, it’s bizarre to me that it’s able to run more than 6 applications. That’s the magic of the operating system.The most fundamental piece of hardware in a computer is its CPU. The CPU (central processing unit) executes instructions given to it and performs logic computations very quickly. In this article, we’ll talk about how the operating system makes it seem like all the programs on your computer have exclusive access to the CPU resource, when in reality, it’s shared across all of them.