Maximum number of applications a CPU can support?

[Entropy.]

Hullo, 

         I've been trying to do a little basic research on how a cpu works, and primarily, how many applications a CPU can run simultaneously. So the CPU has physical cores- but what exactly does that determine? When running applications, say, youtube, could a 4-core hyperthreaded processor only run 4 youtube videos totally simultaneously? In that context, what would hyperthreading do? I've heard that it's essentially using the CPU to extremely quickly switch between two applications? What would happen if you say, opened more than 8 youtube videos at once? Would the CPU be able to support that? Finally, say that each youtube video would put every physical core of the CPU under full load. Would that change anything? Would the CPU be able to still run 8+ applications of a youtube video at once? Sorry for the noob questions lol, I'm just really struggling to find a source that explains it. 

[WereCatf]

1 minute ago, Brok3n But who cares? said:

could a 4-core hyperthreaded processor only run 4 youtube videos totally simultaneously?

Not quite that simple. It could run 4 single-thread applications simultaneously, yes, but e.g. playing a Youtube-video involved tons of threads, including the OS's own processer, drivers, the browser etc.

3 minutes ago, Brok3n But who cares? said:

In that context, what would hyperthreading do? I've heard that it's essentially using the CPU to extremely quickly switch between two applications?

No. Hyperthreading doesn't deal with applications, it deals with CPU-instructions. When the core is working on some instructions, like e.g. floating-point maths, hyper-threading allows the integer-processing part of the core to work on integer-instructions at the same time, ie. hyper-threading is about allowing different parts of the core to work on instructions at the same time as long as those instructions do not need to use the same part of the core.

4 minutes ago, Brok3n But who cares? said:

What would happen if you say, opened more than 8 youtube videos at once? Would the CPU be able to support that?

A CPU doesn't deal with applications, it deals with instructions. The only limit as to how many processes can be running is the size of the task-switching tables -- too much of an advanced topic for you.

7 minutes ago, Brok3n But who cares? said:

Finally, say that each youtube video would put every physical core of the CPU under full load. Would that change anything?

No, since the CPU still doesn't deal with applications, but instructions. With 8 processes, you have twice the amount of instructions than you'd have with 4 processes, ergo it'd take twice as long to process them.

[Entropy.]

8 minutes ago, WereCatf said:

Not quite that simple. It could run 4 single-thread applications simultaneously, yes, but e.g. playing a Youtube-video involved tons of threads, including the OS's own processer, drivers, the browser etc.

No. Hyperthreading doesn't deal with applications, it deals with CPU-instructions. When the core is working on some instructions, like e.g. floating-point maths, hyper-threading allows the integer-processing part of the core to work on integer-instructions at the same time, ie. hyper-threading is about allowing different parts of the core to work on instructions at the same time as long as those instructions do not need to use the same part of the core.

A CPU doesn't deal with applications, it deals with instructions. The only limit as to how many processes can be running is the size of the task-switching tables -- too much of an advanced topic for you.

No, since the CPU still doesn't deal with applications, but instructions. With 8 processes, you have twice the amount of instructions than you'd have with 4 processes, ergo it'd take twice as long to process them.

Okay. As you could probably tell from how I phrased my question, I'm only really familiar with very high-level systems, and because of that, A lot of your explanation is somewhat beyond me. Do you have any recommendations on where I could go to start learning more about this topic to the point where I could understand it? Well, at least somewhat. 

[WereCatf]

1 minute ago, Brok3n But who cares? said:

Do you have any recommendations on where I could go to start learning more about this topic

Not really, no. Search for e.g. "how does a CPU work" on Youtube, I guess?

[Mling]

SMT https://en.wikipedia.org/wiki/Simultaneous_multithreading

A single core can run multiple applications.

It's limit would be how demanding each application is.

In linux you can see this as "Load average" under the program htop.

[Entropy.]

Just now, WereCatf said:

Not really, no. Search for e.g. "how does a CPU work" on Youtube, I guess?

Welp, thanks anyways. Time to watch a 40 video crashcourse on computer science.

[SupaKomputa]

You can use as many applications you want, the problem is it will be limited with how much instructions that the cpu can process.

All those apps instructions will simply goes on queue before getting calculated.

Doesn't matter how much a restaurant accept customers, the problem is how many chefs can complete the orders.

All those orders will need to wait until the chefs can cook them.

Hyperthreading works like a chef having two stove instead of one. It doesn't make the food cook twice faster, since there's only one person to cook it, but at least he can work on the other stove while waiting for the 1st stove to complete.

Sorry for the bad analogy.

[Mling]

I recommend the minix book by Tanenbaum. Just read the first chapter. you should be able to find it online.

[Entropy.]

1 minute ago, Mling said:

I recommend the minix book by Tanenbaum. Just read the first chapter. you should be able to find it online.

Hmm thanks for the recommendation. I'll try it out 

[Entropy.]

4 minutes ago, Mling said:

I recommend the minix book by Tanenbaum. Just read the first chapter. you should be able to find it online.

Operating Systems Design and Implementation (3rd Edition) (droppdf.com)
So this is the book? You reccomend reading the introduction, and 1.1-1.7?

[Mling]

3 minutes ago, Brok3n But who cares? said:

Operating Systems Design and Implementation (3rd Edition) (droppdf.com)
So this is the book? You reccomend reading the introduction, and 1.1-1.7?

yes that is the book. read the intro and chapter 2

[bowrilla]

4 hours ago, Brok3n But who cares? said:

 I've been trying to do a little basic research on how a cpu works,

If you really want to understand how computers work: https://www.youtube.com/c/BenEater/videos

 

But be warned. That's a deep dive.