Wednesday, January 26, 2011

Free command with -o option

Hi,

What does free command witj -o indicate , man page says it disables buffer adjusted line. It subtracts buffer memory from free memory. What does this mean

  • Buffers and cache use up memory. The used/free values include display memory being used when it is consumed by buffers and cache. See this page for a description. http://www.linuxatemyram.com/

    Here is the difference on my system. Basically my system has 2,282,608 kbytes of memory that could be used by programs if it was needed. But a significant portion of that is currently being used for buffers/cache which speed up the normal operation of the system. If a program requested RAM the memory allocated to the cache would be released and allocated to the program.

    cfrancy@enterprise:$ free
                 total       used       free     shared    buffers     cached
    Mem:       3934188    3619656     314532          0     778412    1189664
    -/+ buffers/cache:    1651580    2282608
    Swap:      4882424        960    4881464
    
    cfrancy@enterprise:$ free -o
                 total       used       free     shared    buffers     cached
    Mem:       3934188    3619464     314724          0     778416    1189672
    Swap:      4882424        960    4881464
    
    Prix : +1 cookie well explainned
    From Zoredache
  • In addition to what @Zoredache said the calcs are like:

    how much memory is really being used:

    used - (buffers + cached)
    

    how much memory is really free:

    free + (buffers + cached)
    

    With the above calculation, it makes more sense now (-/+ buffers/cache:)

    "minus buffers and cache" for the used column and "plus buffers and cache" for the free colum

    From Prix

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