# phuong @ localhost in ~ [11:54:54]
$ free -h
total used free shared buff/cache available
Mem: 15G 2.6G 9.8G 95M 3.2G 12G
Swap: 7.9G 0B 7.9G
Lets explain these parameters:
- total: Your total (physical) RAM (excluding a small bit that the kernel permanently reserves for itself at startup); that’s why it shows 15 GiB , and not 16 GiB
total = used + free + buff/cache
- used: Memory in use by the OS (calculated as total – free – buff/cache)
- free: Memory not in use
- shared: Memory used mostly by tpmfs
- buff/cache: Sum of buffers and cache
- available: Estimation of how much memory is available for starting new applications, without swapping. Unlike the data provided by the cache or free fields, this field takes into account page cache and also that not all reclaimable memory slabs will be reclaimed due to items being in use
- swap: Gives information about swap space usage (i.e. memory contents that have been temporarily moved to disk).
What is the difference between buffers and cache?
- A buffer is a temporary location to store data for a particular application and this data is not used by any other application. This is similar to bandwidth concept. When you try to send burst of data through network, if your network card is capable of sending less data, it will keep these huge amounts of data in buffer so that it can send data constantly in lesser speeds.
- In the other hand, Cache is a memory location to store frequently used data for faster access.
- Other difference is that cache can be used multiple times where as buffer is used single time.
- Both are temporary store for your data processing.