Using NAT increases CPU utilization to 60%

bandit · Post by **bandit** » 10. Aug 2008, 01:16

Hi all,

I have Windows XP sp2 guest installed on Ubuntu Hardy(8.04) on Dell Inspiron 9300. Even when the guest is completely idle cpu utilization of Virtualbox hovers around 60%. By hit and trial I found that when I disable NAT(change NAT to Not connected) CPU utilization falls to ~7%. I have tried changing network adapters from PCNet-Fast III to Intel PRO 1000 T. But the problem persists. FYI my laptop is 1.7Ghz Intel Centrino with 1.5GB RAM. and I have not installed any updates on windows xp.

Please suggest a way to fix this problem.

Thanks in advance
EDIT: I am using Sun xVM Virtualbox v 1.6.4

Post by **frank** » 10. Aug 2008, 21:19

Does this host CPU load somehow changes if you run two concurrent VMs (both idle)?

bandit · Post by **bandit** » 11. Aug 2008, 05:08

I have not tried using multiple vm's as I have just one image.

bandit · Post by **bandit** » 13. Aug 2008, 23:20

*bump*

anybody......?????????

Post by **frank** » 15. Aug 2008, 13:42

It would be very easy for you to create a second VM. Just use some live CD, for instance Damn Small Linux, and boot it as a second concurrent instance. It is really possible that the idle load decreases as a second VM will change some internal VirtualBox parameters which may influence the host load.

bandit · Post by **bandit** » 21. Aug 2008, 03:37

I tried running second virtual machine and found out a peculiar occurrence. I ran ubuntu 8.04 as second vm. Here are my observations:

case 1:
Both VM's are running(idle) and no messenger application is running.
Windows: ~5%(on host) and 0-4%(on guest)
Ubuntu: ~5%(on host) and 0-4%(on guest)

case 2:
Both VM's are running(idle) and googletalk/yahoo messenger is running(i.e network is being accessed continuously)
Windows: ~20%(on host) and 30-40%(on guest)
Ubuntu: ~5%(on host) and 0-4%(on guest)

case 3:
Ubuntu is shutdown and only windows VM is running with googletalk/yahoo messenger running in background.
Windows: ~59%(on host) and 0-4%(on guest)

case 4:
Only windows VM is running with no messenger application running.
Windows: ~6%(on host) and 0-3%(on guest)

Strange observation is that Cpu utilization peaks as soon as network is accessed. But the spike is severe when only windows is running.
Second CPU utilization of guest (windows) increases when second vm is running. The excessive cpu is being used by messenger applications. but if I shutdown ubuntu vm CPU utilization on host increases(as stated in case 3) and cpu utilization on guest decreases (as stated in case 3). Hope I have clearly explained my observation.
If you want to me to perform some different experiment I can do that as well.

Thanks

bandit · Post by **bandit** » 24. Aug 2008, 18:29

*bump*

paulsiu · Post by **paulsiu** » 25. Aug 2008, 03:50

Have you check what activity windows is doing during those cpu utilization? For all I know, it could be downloading a huge update or installing a huge update that you keep killing.

Post by **Sasquatch** » 25. Aug 2008, 11:29

paulsiu wrote:Have you check what activity windows is doing during those cpu utilization? For all I know, it could be downloading a huge update or installing a huge update that you keep killing.

That does not explain why it would use considerably less CPU when a second VM is running. It could be coincidence, but I doubt it. From the moment he shut down one of the two guests and network is used by the other VM, CPU goes through the roof, but if he starts the second VM again, CPU goes down.

bandit, do you have the same CPU usage if you create a new Windows VM? You don't have to activate it, as it's only a test and will be discarded before the 30 days end (unless it solves your problem, then you can keep this VM

). If the new VM does not cause this behaviour, there is some sort of conflict acting up that cannot be described.

bandit · Post by **bandit** » 26. Aug 2008, 20:45

I can try creating a second windows VM and see if CPU utilization is affected.

Post by **Sasquatch** » 26. Aug 2008, 21:01

Thanks. It's really strange what you have. I have several Windows Guests, and if I run one or several at a time, none give me high CPU usage.

Post by **TerryE** » 26. Aug 2008, 23:02

Are you using the correct HAL. See this post for a discussion of what to check.

bandit · Post by **bandit** » 28. Aug 2008, 04:10

Thanks. It's really strange what you have. I have several Windows Guests, and if I run one or several at a time, none give me high CPU usage.

I tried installing new windows VM. It has the same problem. If googletalk or yahoo messenger is running then CPU utilization is around 60%. If I close(or signout of) these applications utilization drops to 6% (on idle). CPU utilization is only high when an IM application is running. I tried installing skype but due to unknown reason skype crashes the moment it starts. I think the problem has something to do with network access.

Are you using the correct HAL. See this post for a discussion of what to check.

I checked the thread. Seems the problems are unrelated.

Post by **Sasquatch** » 28. Aug 2008, 11:21

Does it happen with every IM client? I don't have Google Talk or Yahoo! Messenger, but I can test it with Trillian and MSN messenger. However, now that I think about it, I didn't have high CPU with those clients too (at least with Trillian for MSN).

bandit · Post by **bandit** » 28. Aug 2008, 15:41

I tried using windows messenger. The problem persists.