The word comes from the original purpose of the cache computer system architecture, provide a "buffer" is to allow data access speed adaptive processing speed of the CPU, memory based on the principle of "local sex program execution and data access," that within a certain space and program execution time, the code focused on a portion to be accessed.
Today cache concept has been expanded, not only between the CPU and main memory have Cache, but also in the memory and hard drive between there Cache ( disk cache ), and even the hard disk and network between also has a sense of Cache── said as Internet temporary folder or web content caching. Any of the velocity difference between two large hardware between, both the structure for coordinating data transfer speed difference, may be referred to as Cache.
Here it is that HTTP caching on the Web.
Caching purposes
- Reduce redundant data transmission
- Alleviate network bottlenecks
- Reduce server load
- Faster response
Cache classification
- Private cache
- Public cache
Private cache for individual users, such as our browser built private cache; for an internal group, such as a company, we can also set up a caching proxy server for this group, this is a public cache. Proxy cache will involve many things, supplemented later.
Cache structure
The above mentioned cache classification on public and private cache buffer, both of which tend to be in a network architecture there, and this is the cache hierarchy, in addition to the hierarchy, as well as more complex network cache and other structures, the article does not discuss in detail.
Cache parameters
- Byte hit ratio: the ratio of buffer to provide a percentage of all bytes in the byte transfer
- Cache hit rate (document hit rate): the proportion of the provided cache request