What is the difference between pre-fetching, cacheing, and bufferi

[Guest b11_]

What is the difference between pre-fetching, cacheing, and buffering?

[Guest HEMI-Powered]

Re: What is the difference between pre-fetching, cacheing, and bufferi

 

=?Utf-8?B?YjExXw==?= added these comments in the current

discussion du jour ...

> What is the difference between pre-fetching, cacheing, and

> buffering?

>

My defs are likely out-of-date and are certainly not technically

rigorous, but here goes:

 

1) Pre-fetching is when the O/S attempts to anticipate the next

sectors/blocks/segments of a file or files to read from next

based on what it has been asked to "fetch" so far. This works

quite well when the file in question is quite large or the O/S

"knows" that an EXE will need DLLs, etc.

 

2) Caching is the process of storing often-used information

either in memory where it can be retrieved very quickly or to a

contingous block of HDD space that has been set up to quickly

write and read from by the O/S. Obviously, the more memory you

have, all other things being equal but they seldom are, the

greater chance of caching to memory. As to HDD "caching", one

might consider c:\pagefile.sys to be such a system.

 

3) Buffering means to use some very high-speed storage, such as

memory, to balance the slower speed of an output device to the

very high speed of the CPU. The term was first used in the days

of reel-to-reel magnetic tape and the multi-disc removable

platters of early hard drives. Someplace had to be found to

temporarily store the information until the tape, disk, or even a

line printer, could process it. In my early mainframe days,

buffering was usually done to the primative core memory of the

day but was also used to store lower priority data to a temp file

on a hard disk platter someplace for later processing.

 

Hope this helps and I also hope somebody comes along whose both

more up-to-date than me and also more technically proficient!

 

--

HP, aka Jerry

 

"Surely you jest - and don't call me Shirley!" - from the movie

"Airplane!"

[Guest Bob I]

Re: What is the difference between pre-fetching, cacheing, and bufferi

 

Start here

 

http://en.wikipedia.org/wiki/Prefetcher

 

b11_ wrote:

> What is the difference between pre-fetching, cacheing, and buffering?