virtualbox.org

Hi all, I have the following setup -

Host - Windows 7 32 Bit 4GB Ram

Guest - Cent OS 6.2 with the gnome desktop / 1GB Ram and 1 CPU

I have setup the guest and its working fine but the network perfomance is very slow.

On the guest I do a speed test and I am lucky to get 20mb's a second download but on the host I get 70 - 80mb's.

I have tried changing the network cards and have used both bridge and nat but they get the same results.

I have also checked the duplex setting and it is registering as gigabit ethernet on the guest.

Is this expected behaviour of running linux in virtual box that you loose significant network performance or am I possibly missing something?

Thanks!

Use the paravirtualized network adapter in the guest settings.

Thanks I tried that and no good...

Speed test on the host is 80mbps a second from a local test site.

Speed test on the guest (Centos 6.2) is 10mbps from the same site.

Its a huge difference, any ideas?

Not really. I have close to the same speed in all of the guests I control/manage. I always use paravirtualized network drivers because they are close to 3 times faster in a virtual guest. I would look at the guest and make sure the MTU and other settings are defined properly. I believe I have access to a CentOS guest and will test it later today and see what I get.

OK I am DLing a cd image and it is coming through at the same speed as I get on the host.
One thing that you also need to realise is these speed tests are not really what you need to do a real test. Download a file (at least a few hundred MB) on the host and then on the guest and compare the time it takes.

Cheers for the prompt responses Perryg....

I just tried another computer that is a little bettter speced and grabbed an 800mb iso.

Guest = 50 - 60mbps

Host 80 -90mbps

Much better but still a significant difference...

If the guest was Linux then I would say you need to learn how to tune it. Linux is conservative with network buffers which only shows up on large file downloads.
I have actually seen some of my guests with the VirtIO (paravirtualized) drivers DL faster than the host but that is because I have not tuned my host for large file downloads.