Free (command)

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free [1] display amount of free and used memory in the system

free -h
             total        used        free      shared  buff/cache   available
Mem:           503G         21G         43G        2.1M        438G        478G
Swap:          975M         50M        925M
free
             total        used        free      shared  buff/cache   available
Mem:      528029540    22891532    48868648        2128   456269360   501718128
Swap:        999420       51456      947964

No swap configured:

free -h
             total        used        free      shared  buff/cache   available
Mem:           985M        468M         79M         65M        437M        302M
Swap:            0B          0B          0B
free -g

Activities[edit]

  1. Emptying the buffers cache: free -h && sync && echo 3 > /proc/sys/vm/drop_caches && free -h[2]
  2. Use fio with direct=0 to fill up your cache.
  3. Review historical memory usage with: sar -r --human
  4. Review /proc/meminfo
  5. ps -eo pid,user,s,comm,size,vsize,rss --sort -size | head

See also[edit]

  • http://man7.org/linux/man-pages/man1/free.1.html
  • https://unix.stackexchange.com/questions/87908/how-do-you-empty-the-buffers-and-cache-on-a-linux-system