virtualbox.org

I have a problem with the latest Virtual Box release. Starting a virtual machine (it is unimportant whether the guest has a network card defined, is using NAT or bridging - it is sufficient that at least one guest is startet to cause problem) the host network transfer speed slows down from 55MB/s to 6-10 MB/s (between the host and a second machine (not the guest) - gbit speed). Stopping all virtual machines the network speed is instantly restored to the average of 55MB/s. This problem occures on a vista 64-bit core i7 machine with a realtek gbit card and a core 2 duo windows 7 machine with marvell gbit card. I have tested both as host machines with the latest virtualbox software.

Any Ideas?

Guest settings? cpu Host use when Guest is running?

Regardless of the guest settings - the network throughput on the host is very slow - even with only one guest startet and this guest not having any network adapters. The cpu host use is smaller than 10%. Stopping all guest the network speed is back to normal instantly. Both pc behave the same. I have tested with vmware workstation 7 on one of them and the network behaves normal while virtual machines are running, but I would prefer virtualbox... Everything is working fine - but the network slow down.

Hello,
i think you have the same (and ignored) problem i posted here. http://forums.virtualbox.org/viewtopic. ... rk#p106891 and Majesty00 posted here http://forums.virtualbox.org/viewtopic. ... 74#p123374

I had the same problem on my Windows 7 64bit HOST.
But then I've deinstalled VirtualBox completely, rebooted and installed VirtualBox 3.2.4 again. Now the network speed is as high as limited by the provider.
Today I've updated to 2.1.6 and the network speed is still high for both HOST (Win7 64bit) and GUEST (WinXP 32bit SP3).

That is very interesting. The fact that it went away on a rebuild indicated that it is something odd happening (as does the fact that only a few machines have this problem). My guess is that it is some odd condition in the NIC driver caused by adding the VBox filter driver which happens when you install VirtualBox). The filter driver works with the NIC driver to sort out which packets go to the host and which go to the vm.

The fact that it happens to the same person on two machines with a different OS and a different NIC doesn't fit too well with that theory. I certainly don't see the problem with Windows 7 x64 on an i5 750 with a Broadcom gigabit NIC.

I've to correct my last posting. The solution was not really stable.

But now I found the reason: The BIOS setting for CPU C State Capability [Cn]
With C3 it works fine but with C4 it worked weak as described.

My hardware: ASUS P5N-E SLI with newest BIOS, Intel Core2Duo E8400, 4 GB RAM, ASUS GeForce 8600 GT and enough HDD space connected via SATA
My software on HOST: Windows 7 64bit, Kaspersky IS 2011, VirtualBox 2.1.6, and a lot more