What is CPU Cache?

CPU cache is among the fastest kinds of memory in your system, but what does it do, and why is it so important?

[Goabnb]

Imagine memory like a builder with tools.
Hard drive is the shop that sells tools. Lots of tools to choose from but a lot slower as he'd have to drive to get them.
RAM is like his van. Smaller in size, but a lot faster for him to access and do his work.
L3 cache is like his tool belt. Right on him, very small range, but incredibly quick to access, barely slows him down at all.
L1 & L2 cache are like the tools in his hand. Even more limited, generally only one tool at a time, but incredibly quick to use as he doesn't need to even grab them, they are stored right there ready for immediate use.

[BeastOrGod]

Woow, Linus hit puberty hard! He is huge!

[dapperbrick]

"Cash with an E"
So you're talking about Cesh?

[ThePreyBrigade]

"Cache with an 'E'"

That is... not the only difference...

[_Zekken]

this actually explains so much because I have never had a clue what the CPUs Cache does and how significant it is.

[topshicret]

SRAM in Polish is literally "I'M SHITTING"

[parallaxggyt]

I'm using a hard drive for my cache it's really fast.

[momeningod]

don't scroll down to the comments its has nothing related to the video subject
thank you ... thank me later ;)

[Narwaro]

Registers are also a type of memory and they are even faster! But very small at the same time. (512 byte per core on Intel) As the processor can only process data that are stored in registers (needs to be loaded from RAM to cache and from cache to register), organizing cache hierarchy is one of the most important things apart from the actual processing.

[Funnydudderdude]

Our ICT teacher showed us this today and i got a bit too excited it was a techquickie video

[DeadockedlEdiTz]

I learned about caching in my CS classes and this was a great simplistic overview of what the cache is/does!

[tonyhuynh]

I don't have alot of cache but do you take debit?

[CrispyHulk]

Informative, well paced and with interested editing. This is an example of a perfect tech explanation video! Thanks

[BrownieX]

I didn't think this would be that accurate. But you covered all the basic points. You guys are really doing your research. I appreciate that.

[cdngamereh]

Played @ 1.25 speed after 5 seconds..
"ah there we go, linus' speed"

[ej_tech]

Most computers now have more cache than a 1.44MB floppy. My laptop with a Core i5 has 3MB L3 cache.

[amj]

My lecturer showed this during our lecture and that was the only time I learned something during her lecturer. Thanks Techquickie!

[RadiusNightly]

To put it in perspective, more CPU cache means CPU can bite more information from RAM, means more data will be done in same amount of time. Manufactures usually scale CPU caches with a CPU power.
For example, cracking ZIP password with brute force attack is usually based on true CPU power, his cores and caches, so...
T9400 are Intel mobile CPU for laptops, it got 2.66GHz speed, got 2 cores, L2 cache of 6MB as 24-ways, using 35W.
Phenom II X6 1100T are AMD desktop CPU, it got 3.3-3.7GHz, got 6 cores, L3 cache of 6MB as 48 way set, using 125W.
So, AMD got like 2 times more GHz, 2 times more transistors, 3 times more cores, additional cache level thats supposed to organize data better and make it faster, and its freaking desktop CPU, but, they both cost same amount of money, both got 6MB of cache, both are 45nm, etc., and tests shows they both have same power, around 27 000 000 passwords per second.
So keep in mind that CPU cache is one additionally factor in processing, bigger cache are like bigger mouth, the more you can bite, the more you can process and eat in same amount of time.

[Soyerz]

Can I please have a job making your hilarious illustrations? They get me every time.

[denverag]

i've always wondered if it would be possible to make an L4 cache, have it be basically as fast as L3 but outside of the processor, in a small LGA or rPGA socket near the processor, with say 600 pins with the pin density of lga2011, but with this dedicated cache socket you could have an al-gore-rhythm that caches, say 1GB of system ram with a 95+% hit rate