CPU Cache Explained - What is Cache Memory?

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What is CPU cache? Now a computer has two  different types of memory. One type is what   is used in RAM modules, which is DRAM or a  dynamic RAM. And DRAM is memory that uses   capacitors to store data and these capacitors  have to constantly and dynamically be refreshed   often with electricity in order for them  to store data. But there's another type of   memory that a computer uses that doesn't have  to be constantly refreshed. And this memory is   called SRAM or a static RAM. And SRAM is what is  used in the CPU cache. And because SRAM doesn't   have to be constantly refreshed, it is a lot  faster than DRAM and it's also very expensive. The CPU cache is the CPU's internal memory.  And its job is to store copies of data and   instructions from RAM that's waiting to be used  by the CPU. So basically what the CPU cache does,   is that it holds common data that it thinks the  CPU is going to access over and over again because   when the CPU needs to access certain data, it  always checks the faster cache memory first to   see if a data it needs is there. And if it's not,  then the CPU would have to go back to the slower   primary memory or RAM to get the data it needs. So  that's why cache memory is so important, because   if the CPU can access what it needs on the faster  cache, then the faster the computer will perform.   So basically the whole idea behind cache is to  make the computer run faster at a cheaper price.   Now a computer can run without the CPU  cache, but it would be a lot slower   because even though RAM is becoming faster,  it still can't feed the data to the CPU fast   enough because CPUs have gotten so fast, that  a lot of times the CPU is waiting around doing   nothing while it waits for more data, and  this creates a bottleneck. So that's why   the CPU cache was developed. So it can  act like a middleman between the CPU and   RAM to assist in feeding the CPU that data it  needs a lot faster which reduces bottlenecks. CPU cache comes in three different  levels. For example there's level 1 cache,   which is also called primary cache, and level  1 cache is located on the processor itself. So   it runs as the same speed as the processor. So  it's very fast and is the fastest cache on the   computer. And there is also level 2 cache, which  is also called external cache, and level 2 cache   is used to catch recent data accesses from the  processor that were not caught by the level 1   cache. So in a nutshell, if the CPU can't find  that data it needs in the level 1 cache, it then   searches the level 2 cache for the data. And if  the CPU can't find the data in the level 2 cache,   then it searches the last level of cache which  is level 3. And level 3 cache is used to catch   recent data accesses that were not caught  by the level 2 cache. And finally if level   3 doesn't have the data, then the CPU has to go  back to the slower RAM to find the data it needs. Now in earlier computers, level 2 cache was  located on a separate chip on the motherboard.   Or in modern CPUs, it would be located on  the processor. Level 2 cache is larger than   level 1 cache but it's not as fast as level  1 cache. And level 3 cache is also located   on the processor. Level 3 is larger than  level 2 but it's not as fast as level 2   cache. Level 3 is often referred to as shared  cache because its memory is shared between all   the cores on the CPU, whereas level 1 and level  2 cache are dedicated to their own CPU core.
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Channel: PowerCert Animated Videos
Views: 917,276
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Keywords: cache, cpu cache, cache memory, cpu cache explained, what is cpu cache, cache memory explained, memory cache, SRAM, what is SRAM, what is cache memory, cpu explained, types of cache memory, l1 cache
Id: yi0FhRqDJfo
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Length: 4min 51sec (291 seconds)
Published: Sun Nov 27 2016
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