Multi Programming - Computerphile

Multitasking is a hoax - clever techniques mean that your CPU is shuffling between lots of tasks, but doing them one at a time. Dr Steve Bagley regenerates his clones to explain...

This video was filmed and edited by Sean Riley.

[kwanarchive]

Computerphile single handedly keeping the dot matrix paper industry alive.

[totlyepic]

You have no idea how happy you've made me by finally increasing the number of actual computer science videos on this channel. You guys are doing a great job.

[jamesgrimwood]

One of the most interesting parts of my Computer Science degree was learning about operating systems by stepping through the Minix source. Although things are more complex now with multi-core CPUs because now more than one thing (or more than one bit of the same thing) can run at the same time.

[konstantinrebrov]

An example of Multi Programming: I'm watching this video while I wait for my code to compile.

[pukkandan]

Why you eating my processes? No wonder my pc keeps crashing

[mannyknowles]

Exquisitely presented. That YouTube plaque in the background is well-deserved. Computerphile remains one of my favorite channels.

[Nayus]

The concept of showing it with the different Dr. Bagley clones is brilliant! and not easy to do!

[jmalmsten]

"... unless the process is just very boring and just kills itself..."

That's a bit... harsh?

(Yeah, I know, it's perfectly usual programming lingo. :) )

[TheAnkMan]

Steve is one of my favourite profs and Computerphile. Also loving the array of vintage computers in the background. Hmm, talking about that: he should do an episode only about them. Show every of them and give a brief history and hardware specs.

[lohphat]

So a 12 core CPU gets you to the diabeetus faster then.

Got it.

[RyanFernandezz]

This was a really fun idea for the editing of the video Sean, great job!

[georhodiumgeo]

My mind is blown.

I just can’t believe they made that exact same shirt in two colors.

[MrJezster]

I have not seen this type of printer paper since 1993 when we used to load it into Honeywell DPS7 mainframe chain printers. Love this channel so much, really interesting.

[Roxor]

I remember hearing about an incident involving MacOS's cooperative multitasking.

Every now and then a network full of macs would stall, then get flooded with packets. It was eventually narrowed down to a specific machine and when the admin went and investigated, nothing seemed to be out of the ordinary. After a few occurrences of this, the admin sat down and watched the user at work. Sometimes when working with the mouse (might have been drawing), he'd hold the mouse button down for much, much longer than was normal, and with the input handler being tied up on the long mouse press would result in nothing else in the computer getting to run, including the network stack. As a result, no packets were passed on from the machine in question and the buffer would just fill up, resulting in a flood when the user released the button and the network stack got some processing time again. A gentle word with the user not to hold the mouse button down so long fixed the problem.

Don't know if it's true or if I remembered all the details correctly. I didn't have any luck tracking down the original before making this post.

[spikeevans]

Very good video. I'd like to suggest looking at I/O scheduling. Both windows and linux can become very unresponsive if doing heavy I/O. I've seen cases, even on a very powerful PC, where responding to a mouse click can take many seconds during heavy I/O (disk backup, file downloads etc). Perhaps look at the various scheduling algorithms and their pros and cons.

[theharbingerofconflation]

Killing them.. I remember having a conversation about host process management from an OS perspective in a café once. Told a guy semi-loudly "Remember that we also need to kill all the children of the host" (referring to child processes) "Before we kill the host."
Coffee lady came by asking whether she has to call the cops on us or whats going on.

[SupaKoopaTroopa]

This is the most clear explanation I've ever herd for this topic!

[maxtaylor]

You guy’s are missing out. When Bagley gave us this lecture we also got to eat the jelly babies.

[ujjal]

Looking forward to both future videos!

[yoloswaggins]

Example of multi-programming: while I'm watching this my evil clones are taking over the world.