Computer Speeds - Computerphile 

I've learned so much about computers because of this channel. I'm very grateful.

The GHz is how fast the little legs move. But some of the runners can carry more, some go through short cuts... some have longer distance to cover. :P

0:12 "Dunno... Anyway, I digest!" Had me in tears 😭😭😭

A nice analogy I like to show is with engines/motors, the clock speed is the RPM, but the key is that the torque is also important, and that "torque" is defined by the architecture, which is where most of the improvements happen between architectures. It starts to fail down when you want to consider instructions which take different times, I still think it's helpful as a quick analogy. :)

I could listen to Dr. Bagley talk about this for hours. It's really important and we are now at a point where we literally can't make processors better just by speaking in terms of clock cycles alone. We require entirely new ideas about processor architecture, because the x86 model is done.

"We can make the pipeline longer" I'm getting visions of Pentium 4...

Why do people dislike these videos? They're so informative.

What I learned today is that Fetch -> Decode - Execute is the meaning of FeDEx

Where do I get an overview of the present/ latest cpu-architectures so I can learn more about them ? thanx

Needed someone to explain this to me properly. Thank you.

is that an Amiga in the background?

The bit he left out is that CPU manufacturers have lenghtened the pipeline precisely to allow faster clock speeds. For example an ARM7 (1995-2005) had less than 10 cycles (about 7 or 9 stages) and because each cyle does more things it's very hard to match timings and get a high clock speed. So newer ARM Cortex (2005-today) have more than 10 cycles in their pipelines (around 15 or more). With more steps, each is smaller so that the overall clock speed can be increased. But with a longer pipeline, a full refill is a bigger waste (compared to a smaller pipeline) hence the mitigation like branch prediction and superscalar instructions (=instruction-level parallelism). It's all a trade-off that works well for some workloads and less well for others.

Thank you for explaining that.

So it's practically impossible to compare processors of similar speeds without benchmark tests and even those are subjective?

Anyone knows what the title is of the orchestra play?

It's super weird how these things progress. The 5W, 1.1GHz m3-8100Y in my new laptop outperforms the 105W, 2.4 GHz Q6600 that was in the first desktop I bought in 2008.

My late 2018 mid/low range Octa-core 1.8 GHz Kryo 260 phone absolutely blows away my flagship Quad-core 2.7 GHz Krait 450 one from 2014. It's amazing what more cores and a few years of development can do.

What's the fastest moderately priced computer I can build, mostly for checking emails and surfing the internet, doing a bit of Photoshop, MS Word, and an occasional video rendering? I currently have an AMD Ryzen 3950x on an Asus Crosshair Hero VI motherboard and an M.2 ssd with Win10 and programs on it, and a secondary internal spinning hard drive for data. What bugs me are the computer glitches created when Windows does an update (I'm sure they do that so people sign up for their tech support program for $150/year), and other various problems. If I update to a newer Asus motherboard will I really see any difference? Also what do you think of Win11? Does it really make anyone's life better? Less glitches is what I need.

Guys please please please make a video about formal verification methods. Great job with this vid!

All very interesting, but the real question is: what do you do with continuous form paper in 2019? :-)

I really wish you went into more detail on Instructions per clock, Its the reason why a MOS 6502 could beat out a Intel chip of the same period when run at the same clock speed.

There is so much things to take into consideration when it comes to comparing architectures and processors. I do find it partly annoying when people in general look at clock speeds or pure core count, or a multiple of the two. While not taking architectural differences into account. Though, a lot of people toss ARM under the buss due to it being RISC, and RISC surely is always worse then CISC. (Not really, depends greatly on the application, and the instruction set.) In the end, comparing two processors can be very hard and vary extremely depending on the application. Heck, even some tasks are faster done on some cheap microcontrollers then on high end architectures...

Can you do a video on microcode and how instructions are decoded and executed?

So it’s kind of like air lock in a fuel system ? Lol. But not. Lol. Still a great explanation. Great tutorial as usual from this amazing teacher. All these guys and girls are friggin top shelf.

I'm confused here, my lectures teach me that clock cycles only act to synchronise circuits but play no role in computation, then here it states that they are the drivers of all computation, which is which??

You cut out the bubble intro :( At 2:53 was the last shot of paper pre-bubble, it shows: 21_ → 321 → 432 → 543 (simple enough...) 3:36 is the next available shot of paper, but it has something completely different now: _43→5_4→65_→765 (a bit more difficult to grasp!) What happened in between!? The answer: Bubble. It was not explained what that is. Just used in the next scene without explanation.

Not only the pipeline. I did some asm. Well, I admit, before long pipelines and predictive arquitecture I know nothing about. I remember: the 8080 where every operation had to be made inside the acummulator, then the Z80 you do ops on any register without the need to move from/to the accumulator saving many instructions. Then some micros with the ability to switch an entire set of registers making multitask more efficient. Then the Wang VS 40 bit long instruction, yo do the operation, increment/decrement one/both Mem Addrss Reg, check status (like zero), set a short jump address... in a sigle 40 bit microinstruction. Then the "RISC" idea, lots more registers (and some cache) area , less microinstructions circuit on complex instructions that are used less than 1% of the time "lets the compiler deal with complex instructions" Any of those makes the clock comparison useless.

The sound of the pen & paper goes through me, every single video!

Are CPU clocks made using crystals? If so, how is it possible to overclock or underclock, since crystals output constant frequencies IIRC? Also how difficult is it for the motherboard to synchronize between components since CPU, RAM, etc. are all clocked differently if I am not mistaken? An in depth video would be cool :)

Is this the reason that al digital devices have system clock in them? As in they want the Fetch, decode and execute to be done in a synchronous manner instead being done all at once which can be dangerous.

Is it reasonable to assume that there's an inverse relationship between clock speed and number of logical gates activated per pipeline stage? My understanding has been that there's generally no magical frequency limit but that we could in theory split a pipeline into so many simple stages that it can run at like 10ghz+ while utilizing the same process to build (assuming such a clock can be accurately generated).

Nice shirt as always

Why are youtube's auto-subs not enabled for this? Is this intentionally disabled by you or did YT didn't get a chance to process it for that yet or... how does that work?

Would it be possible to make a terahertz chip given a completely simplified architecture?

Does all this apply to Risk V?

You guys should do a video on http3

I digest

If I am correct he explained why x86 is faster and arm is slower the x86 can do more single instructions ( per clock) than arm does it in two ( the extended model)

Please enable auto-generated CCs

why subtitle isn't available for this video is beyond me!

Please explain MIPS architecture

Fact of the matter is, regarding General Purpose Use - Clock speed has had a larger factor in quantifiable CPU throughput than 'design' has - looking all he way back to 8Mhz 286's. Little things like MMS (remember that?) added little bits - AES-NI is a massive thing - but these are additional ASIC style development really. For the most part - the software you run isn't scaled / compiled well for the architecture capabilities of the CPU you are running on. UNLESS it's dedicated simulation.

Doesn't this also depend on the instruction set as well and whether it's cisc or risc?

what about the name

So is this what 'instructions per cycle' is all about?

No mention of SIMD vectorization or multicore as a design strategy to mitigate the frequency limit (a 24 core CPU with AVX512 instruction set and 2 FMA units can in theory do 768 double precision floating point operations every clock cycle). No mention of the power and thermal limit that restrict clock frequencies.

I just came here to see what cpu I should buy

Hi, steave...I should glad if you could manage to send one IBM M series keyboard.....pardon me but i can not cantrol my self after seeing that much stuff behind you..!..peace

Having a deja vu, feels like I have been doing the same stuff while hearing this vid once before... of course that can’t be the case but ya know...

Preview image contains Ghz and Ghz. It should be GHz with a uppercase H.

🔥

lolz that printer paper is still used ?? :D

and this is why concurrency is such a headache for programmers. Beware of using parallel or multiple threads that share data.

So is there any way to know how fast a CPU really is compared to others without running tests ourselves?

Will the speed of light be a limit to clock cycles? Is it already? (Say, for how far the RAM is from the CPU, copper traces, etc) I ask this because a fraction of a thousandth of a millionth of a light-second is in the ballpark of just a few centimeters.

Can you do a video on overclocking?

I don't know, I digest. :)

Please, ADD auto-generated subtitles to this video. Very good information, but I am not familiar with the gentlemen's accent, hard to decipher in places

RISC would also speed up the execution cycle.

It's GHz, not Ghz. 1/1 Hz = 1 s, but 1 S = 1/1 Ω.

Hz, not hz.

THz computer will be achievable if you get the compute elements down to being a collection of atoms, and the bus wiring to be single carbon or metal nanotubes, a single atom in diameter.

was hoping to see a video about the utterly amazing speed at which modern processors run and how many billions of things are done in a single second. i don't even think this video even defined what a gigahertz is.

Diet Coke? You need to give Pepsi Max a try.

"I digest" 0:13

Why it was not mentioned the most popular term "IPC"? (and pls, don't try to explain that are instructions per clock... It IS per CYCLE)

Is a 2.8Ghz professor of 2019 faster than a 2.8Ghz processor of 2017? I digest.

Comparing processors based on clockspeed is like comparing engines based on max RPM.

then there's in-order vs out of order execution.

A 2Ghz Pentium 4 is as fast as a 33Mhz 486... "Netburst" was appallingly terrible.

Can't focus on the video...am too lost in this man's shirt

From the description: "aren't enough to measure it's speed" I think you're missing a comma and this sentence is incomplete. It sounds like you meant "aren't enough to measure, it is speed..." and then you just end the sentence there without finishing it. The more I read the description, the less sense it makes. And this is why you should use the correct forms of its and it's. Its is possessive. It's is a contraction of it is. Of course it's still comprehensible with "it's" but it's an important distinction. Some may say I'm being pedantic, but if we're not careful about our grammar, it can cause a lot of miscommunication and potential problems. Just look at all of the mess neglecting the Oxford Comma causes.

A computerphile with mac's? That doesnt compute

"I digest" so do i... so do i

He really does digest

"will we ever get terahertz processors" I would guess yes. as moores law breaks down, eventually we're going to hit a limit on how small you can physically make transistors (right now we're already making them something like 40 atoms across, and you cannot realistically go smaller than an atom, right?) at that point to increase computing power we'll have to either make them larger, which might happen, or it's back to the clock speed wars. (I suppose you could also try and push for higher IPC, but that will only get you so far)

Ok.. explain that again.. only imagine that I have no knowledge of computers.. whatsoever.

Video Description, "...measure it's speed." It's 'its', not 'it's'.

"2Ghz" triggers me in so many ways.

It doesn't matter, when the Gallium Arsenide chips instead of silicon everything will be much more faster... I was promised... last century... Mmm... Shouldnt be ready already...? Helloooo???

GIMPS - Great Internet Mersenne Prime Search давай найди все тесты 52 чисел быстрее 8 лет

Bill gates looks young in this video

What does the fox say 🤣

This is especially relevant with amd's 64 core 128 thread 7742 server cpu.

Marry me Steve

Is it just me or is the video extremely quiet

At 00:08 I see Ghz That must be GHz A common but annoying mistake.

😰😰😰

🥴

1:07 "hmhm, has only got one ..."

2 adverts, really?

Computerphile is so weird. Sometimes it goes into computer science like lambda calculus or programming concepts. Sometimes it's great history. And sometimes it's this... Incredibly basic, consumer information

Why does everybody seem to forget about ipc when it comes to speed? While most modern CPUs have ~5ipc, Mill computing will have a CPU with 33 ipc. That's insane! Ah, what am I thinking? Normies care about the app experience, not the specs LOL

"I digest" a nice Freudian slip ;-)

I think you don't know what your doing ,now i know less.

He said in 6 minutes what could've been said in 3 sentences.

Second

install Emacs

first

Computers DO NOT need to keep getting faster, "PROGRAMMERS" (drag'n'drop merchants these days!) *NEED* to stop being so SLOPPY AND LAZY.