Linux: Memory

linux-memory

[sean.humbarger@ISS203943 ~]$ free -m
             total       used       free     shared    buffers     cached
Mem:         16006       1434      14572          0         50        575
-/+ buffers/cache:        808      15197
Swap:         7871          0       7871

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'Mem' Row 'total' Column
  * This is the total amount of RAM installed on your machine. It is the sum of the 'used' and free columns on the same row
  
'Mem' Row 'used' Column
  * This indicates how much RAM is currently being used. It is the sum of the 'buffers' and 'cached' columns on the first line plus the 'used' column on the second line.
  
'Mem' Row 'free' Column
  * This indicates how much memory is currently available on the system
  
'Mem' Row 'shared' Column
  * According to the man pages (http://linux.die.net/man/1/free), this column should be ignored because it is obsolete
  
'Mem' Row 'buffers' Column
  * Memory used by the kernel buffer cache.  
  * The kernel buffer cache is used to speed up disk operations by allowing disk reads and writes to be serviced by memory.
  * The memory is reclaimed if it's needed by applications on the system
  
'Mem' Row 'cached' Column
  * Indicates how many memory pages have been cached for faster access later
  * The memory is reclaimed if it's needed by applications on the system
  
'-/+' Row 'Used' Column
  * Indicates memory that is actually be used by the applications

'-/+' Row 'Free' Column
  * Indicates memory that is avaialable for use by applications. 
  * Since the 'buffer' and 'cached' columns in the first line can easily have their memory reclaimed, this value is the sum of the 'free', 'buffers', and 'cached' columns on the first line.