Why does top show 730MB of RAM used, but the "Task Manager" shows 190MB?

Some more information on my system:

  • Lubuntu 14.04
  • VirtualBox


top in terminal

Task Manager


2 Answers 2


Because it includes cache and buffers in top (you can see them as individual items to the right of the total memory).


I believe i found the answer:

To understand the process architecture of VirtualBox see The VirtualBox architecture :

Once you start a virtual machine (VM) from the GUI, you have two windows (the main window and the VM), but three processes running. Looking at your system from Task Manager (on Windows) or some system monitor (on Linux), you will see these:

  1. VirtualBox, the GUI for the main window;

  2. Another VirtualBox process that was started with the -startvm parameter, which means that its GUI process acts as a shell for a VM;

  3. VBoxSVC, the service mentioned above, which is running in the background to keep track of all the processes involved.

This was automatically started by the first GUI process.

The source with more information.

  • 2
    Could you please clarify how this is relevant? The OP is presumably showing the top output of the guest OS, and anyway what you show has nothing to do with memory usage, only with the number of processes launched by virtualbox.
    – terdon
    May 17, 2014 at 15:23
  • @user279450 do you mean if I install lubuntu on a real machine, those numbers will be the same? But I don't understand the relevance.
    – Rahmani
    May 17, 2014 at 15:28
  • well, it seems i am wrong. What i thought was because you have your normal processes(windows) and you add more in virtualbox, your windows will read it's own and virtualbox has some extra in it's own environment. Maybe misthinking of me, maybe a language barrier. Thats why you are here ;)
    – user279450
    May 17, 2014 at 15:35

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