1.4.0 (and earlier versions)

mikeshappell · Post by **mikeshappell** » 10. Jun 2007, 03:38

I noticed that unlike other virtual machines I have tried (like Parallels), virtualbox consumes twice the assigned memory per VM. For example, I have a Windows XP VM that is assigned 512MB of memory. Starting the VM, however, consumes 1GB of memory. The VirtualBox process has around 528MB allocated and the rest is not obvious. However, closing down the VM does release about a GB of memory. This may have been discussed in the past and I apologize if I missed the post. Thanks.

Mike

Cogar · Post by **Cogar** » 10. Jun 2007, 06:17

I suspect that some of your measurements may be off, since 500MB is a lot of "not obvious" memory. For example, as a test I am currently running a Linux guest on a Windows host where a base memory of 256 MB was assigned to the guest. Checking the Task Manager in Windows reveals 297,424 K being used by VirtualBox.exe, 20,388 K used by vmserverdWin32.exe, a second process called VirtualBox.exe that uses 11,212 K, and a process called VBoxSVC.exe that uses 9,036 K. There are probably a few smaller ones listed in there with less obvious process names, but that total for all processes is probably in the 350-360 K range. I would consider an overhead of 100 MB to be reasonable to constuct a "hardware machine" out of software.

Let me add that I also run VMs on Windows and Linux hosts to which I have assigned a base memory of 512 MB to the guests. That machine has 1GB of physical memory. If VirtualBox really took twice the alloted memory, the machine would run out of memory for the host, but both the host and guest systems seem to be operating normally--even with multiple applications open on both.

achimha · Post by **achimha** » 10. Jun 2007, 09:25

There are only VirtualBox.exe and VBoxSVC.exe. Other processes do not belong to VirtualBox. The guest RAM is allocated by VirtualBox.exe. VBoxSVC.exe is just a helper.

Most other products do not show the guest RAM allocation in top/task manager but hide it due to the way they do the allocation. VirtualBox shows the full amount of guest RAM.

Cogar · Post by **Cogar** » 10. Jun 2007, 16:07

Thank you for the clarification, achimha.

mikeshappell · Post by **mikeshappell** » 11. Jun 2007, 03:20

So like I said, the VirtualBox process is allocating 528MB, but when I close the VM, approximately 1GB is freed. This is virtualbox 1.4.0 on a Vista host. I'd like to be able to run more than one VM at a time, but with each one consuming 1GB, even with 2GB of physical memory, it is not possible. I'd like to understand why I am seeing twice the allocated RAM being consumed when starting a VM. Any thoughts? Thanks.

Mike