Strange CPU usage between guests

Discussions related to using VirtualBox on Windows hosts.

Strange CPU usage between guests

Postby hege » 3. Oct 2007, 09:59

Hi, I have VBox 1.5.0 on XP host.

2 guests, XP and Linux, both idling at 0%. Additions installed.

When I stress Linux guest with compiling etc, hosts task manager says CPU usage is:

VirtualBox.exe 50-80% (Linux guest)
VirtualBox.exe 20-50% (XP guest)

When I stress XP guest, the usage looks normal:

VirtualBox.exe 0% (Linux guest)
VirtualBox.exe 99% (XP guest)

Why does the usage of Linux guest affect the XP process? Is this a bug or some architecture stuff I missed? The Linux guest does seem sluggish when compiling stuff etc compared to VMware.
hege
 
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Joined: 3. Oct 2007, 09:16
Location: Finland

Postby hege » 19. Nov 2007, 08:58

Actually I just need to run something heavy like unpacking archives etc on my host, it also results the idle guest VirtualBox.exe to eat 40% CPU or so.

Am I the only one huh?
hege
 
Posts: 46
Joined: 3. Oct 2007, 09:16
Location: Finland

Postby the4thchild » 19. Nov 2007, 22:22

I think that others are seeing this issue as well, on Linux hosts as well (eg http://forums.virtualbox.org/viewtopic.php?t=2756). I attempted to collect links to some of the relevant discussions here:

http://www.virtualbox.org/ticket/894
the4thchild
 
Posts: 27
Joined: 10. Sep 2007, 05:30
Location: San Francisco, CA
Primary OS: MS Windows 7
VBox Version: PUEL
Guest OSses: MS Windows Vista, MacOS Snow Leopard, Ubuntu 9.10

Postby hege » 31. Dec 2007, 13:29

Seems to be something funny with process priorities.

If I change a guest to LOWER priority than the other one, then the lower priority one gets 99% like it's supposed to and the usage doesn't leak to the idle guest.
hege
 
Posts: 46
Joined: 3. Oct 2007, 09:16
Location: Finland

Postby hege » 21. Jan 2008, 13:39

One way to replicate this with one guest running is to play some video (on the host). When the video player is at same or higher priority than guest, then the guest process uses CPU for no apparent reason. When I lower player priority below guest, everything returns to normal.

Maybe it has something to do with graphics, since running high CPU applications like prime95 doesn't get this effect.
hege
 
Posts: 46
Joined: 3. Oct 2007, 09:16
Location: Finland


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