virtualbox.org

I'm using VB 2.0.2 on a WinXP pro host to run an Ubuntu 8.04 guest (additions installed). Mostly I find VB is great! Fast and responsive! But, whenever I use the network, VB just chews up cpu (running on a Core 2 Duo E6550). Copying a large file from my server (separate physical machine) takes an entire core. The same copy on the host side takes at most 5% cpu. Downloading a torrent takes between 15% and 40%.

I've tried all 4 different NICs to see if there was a difference (Intel's seem slightly better). Also, using this same VM with VMware, the networking only uses ~ 5-10% cpu.

Is this just the way that VB rolls, or is there something I should check? BTW I'm using HIF networking and my physical NIC uses jumbo frames. I haven't tried switching that back to regular, it doesn't seem like it should matter (especially w/ the torrents).

thx

Jumbo frames are not supported for the HIF setup. So turn it down to default. This was mentioned in either one of the changelogs or the manual IIRC.

Actually, the v2.0.0 changelog says that jumbo frames DO work. And this thread http://forums.virtualbox.org/viewtopic. ... ight=jumbo seems to indicate that turning on jumbo frames in the guest may improve the cpu usage!

Thanks!

VirtualBox has limited support for so-called jumbo frames, i.e. networking packets with more than 1500 bytes of data, provided that you use the Intel card virtualization and Host Interface Networking. In other words, jumbo frames are not supported in NAT mode or with the AMD networking devices; in those cases, jumbo packets will silently be dropped for both the transmit and the receive direction. Guest operating
ystems trying to use this feature will observe this as a packet loss, which may lead to unexpected application behavior in the guest. This does not cause problems with guest operating systems in their default con?guration, as jumbo frames need to be explicitly enabled.

As says the manual. Indeed, I was wrong. They are supported.

Huh, I searched the help files and it didn't come up with anything for jumbo frames. Weird... thanks for finding that tho.

Just FYI, I turned on jumbo frames in the guest (matching my setting on the host) and it seems like it may have helped lower the cpu load slightly. Could just be wishful thinking though.

It would be great if I could attach my VM to a physical NIC, since I've got a couple extra lying around. Maybe in the future...

Thanks again for your help