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Dandyman
Asked: 2012-03-13 11:00:02 +0800 CST

Different memory types in System Monitor

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On the ubuntu system monitor there are different types of memory listed: Virtual Memory, Resident Memory, Writeable Memory, Shared Memory & X Server Memory. What are the differences between them, and which reflects the actual RAM usage of the process?

Sorry if it's a newbie question :)

system-monitor memory ram

3 Answers

  1. Best Answer

    • Virtual memory accounts for all the libraries and executable objects that are mapped into your process, as well as your stack space.

    • Resident memory is the amount of memory that is actually in RAM.

    • Writable memory is the amount of address space that your process has allocated with write privileges.

    • Shared memory is memory that may be simultaneously accessed by multiple programs with an intent to provide communication among them or avoid redundant copies.

    • X server memory is the amount used by the X server for the GUI-session.

    References:

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  2. To add on to Ringtail's answer, the plain "Memory" column is Resident - Shared, giving you the memory that the process solely owns.

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  3. Some definitions and wiki pages:

    Virtual_Memory

    Shared Memory: The amount of shared memory used by a task. It simply reflects memory that could be potentially shared with other processes.

    Resident Memory: typically refers to physical RAM installed in the machine

    X Server Memory: Self explanatory, the amount of memory the X server is using (X server controls your user interface)

    Hope I have clarified some things for you.

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