Windows 7 - Can someone please explain cached memory to me very simply.?

Question

What does it do?
What are its benefits?
Disadvantages?

Also what is page file memory and what does it do?

Answer 1

Your computer's processor normally runs much faster than your hard drive. So it spends a lot of its time waiting for the hard drive to sent it the information it needs for processing.



A cache is a small amount of memory where the processor can have information pre-loaded. It assumes that if you are running a program or reading a file, that you are going to continue on to the next instruction in the program or the next line of the file. So while the processor is working on the current information, it can have the hard drive load the next set of information in the cache. That way it is immediately available for the processor to use when it finishes the current set of information. This makes the computer run faster.



A page file is similar to that. Only it has to do with the computer's memory rather than its processor. Every computer has a limited amount of RAM memory. If that memory becomes full (because you are running several programs at once or have opened a huge file), the memory has to store some of the information somewhere else temporarily. So it creates a file on the hard drive and puts information it is not using the a second into that file and frees up some of the RAM memory. When that information is needed, it will "swap out" something else and reload the needed information. Thus the name "swap file" is often used for a page file.



You have probably seen this happen many times. You will be reading a document and you go to scroll down, and everything freezes for a couple of seconds before the document finally scrolls. Since you were not using the new section of the document, Windows had swapped it out to the swap file. That moment of pause was it saving something else and then reloading the new section of document for you. That was the page file in action for you.



Benefits? Faster computer (because of the cache) and able to use more programs at once (page file)



Disadvantages? Uses some of your hard drive space for the swap file.



Also accessing a swap file is much slower than keeping everything in memory. So if you limit the page file, the computer will run faster (everything will be in RAM) but be unable to run more than a couple programs at the same time. You would have to decide if that is an advantage or a disadvantage.

Answer 2

Usually 'cache' (sometimes used interchangeably with 'buffer') refers to memory (real or virtual) that's set aside for temporary storage -- think 'scratch pad'. It's used by all input/output components to store information until it's ready to be processed. Your processor needs a primary (very high speed) and a (slower) secondary 'cache' for storing the results of calculations, data, and program code until needed. This is the highest speed memory available, is very expensive and small changes in the amount of it can make a huge difference in the performance between processors of the same model and speed.

Besides the 'size' of the cache, the speed that it can be accessed, or bandwidth, is also very important. The term 'bit-width' (think # of wires) is often used to describe the memory access capability of a device. For example, a graphics card with a memory bandwidth of 128 bits (128-bit) is nearly twice as fast as one with only a 64-bit bandwidth (it's not always twice as fast because sometimes the complete bandwidth isn't needed). This means that a graphics card with a 128-bit bandwidth and only 512 MB of RAM may easily outperform one with a 64-bit bandwidth and 1 GB of RAM.

(By the way, a 'paging file', is Not related to memory, but the way that PC's were designed eons ago, when nobody figured you'd be using 4GB of RAM to run programs that are only 2 MB in size. Back then it was the other way around. The original systems broke up all program data into pieces and 'swapped' the pieces in and out of memory to the hard drive, called 'paging' -- think of a book as a program, and the computer deals with it by breaking it up into chapters. The hard drive storage area that is set aside for these pieces until they are needed is called 'virtual memory', and this archaic system is still so ingrained in the os that it is not recommended that you turn it off, even if you have oodles of RAM. When you get a Windows error that says you're running out of 'virtual memory', it's referring to this ridiculous system, and how it keeps screwing things up even though you have tons of RAM. The pc industry and Bill Gates dropped the ball on this one because they should have worked together to take advantage of new technologies and upgraded the underlying hardware and os as Apple did. Sure there would have been a period of time while people upgraded because the old hardware was no longer sufficient to run the new software, but the systems we have now would be significantly faster, like Apple computers.)

Answer 3

hi there

cache memory is memory that can be accessed much quicker by the processor(cpu) than regular memory....... basically cached memory can be accessed significantly quicker,thats why a larger cache in a processor equates to better overall performance.....

so the benefits as mentioned are better performance in games and applications through much better data access... however larger caches make processors more expensive...but its worth the additional expense

page file is also known as virtual memory... and the page file in simple terms is " a part of the hard drive used as if it were real system memory " .......... in windows vista a similar feature is used in the shape of "readyboost" .... this uses "cached memory" to improve memory performance however in tests "readyboost" works best with 1 to 2gb of memory(ram)

page file can be adjusted in advanced system properties..however i allways recommend using the default settings in the page file.... adjusting the values wont yeild much improvement .....

i hope this helps

good luck !