[vbox-dev] Network adapters speed - possible bug, need insight

Maxime Dor maxime.dor at altherian.org
Fri Apr 26 07:59:15 PDT 2013


I guess that explains that indeed. I think I've tried disabling the TCP seg
offload months ago but I just can't remember exactly.
Regardless, thank you for your reply - at least it's not just me.


On 26 April 2013 15:32, Ivo Smits <Ivo at ufo-net.nl> wrote:

>  Hello Max,
>
> There was apparently a bug in the VirtIO code, which has just been fixed
> in VirtualBox 4.2.12 (according to the changelog,
> https://www.virtualbox.org/wiki/Changelog). I recently discovered my
> VirtIO network interfaces were slow as well, probably because of the same
> bug. Still running VirtualBox 4.2.8, it was solved by disabling "TCP
> Segmentation Offloading" in the guest OS as suggested in the bug report at
> https://www.virtualbox.org/ticket/9380.
>
> Ivo
>
> Op 26-4-2013 1:01, Maxime Dor schreef:
>
> Hello people,
>
>  For a while now, I have been facing some odd network speed issues with
> Virtualbox but wasn't able to pint-point it down... until now !
> Please bare with me while I explain this.
>
>  To give you some background story, the first time I met this issue was
> while testing the speed of a proftpd server running in a Debian Wheezy VM
> on a Linux Wheezy host, both 64 bits.
>  Following the good recommendations of the User Manual aswell as the forum
> folks, I decided to set the NIC to VirtIO. I was also doing this speed test
> via an OpenVPN connection.
> The speed was always stuck at 8 Mbps for some odd reason. A bit out of
> time, I discarded this as the VPN's fault, without further investigation.
>
>  Some months later, I was installing some software (Sage BOB50) in a Win
> 7 64 bits VM which requires access to a Sybase DB, running in a Win2k8 R2
> 64 bits VM.
> And disaster happened : for some reason, the software was just terribly
> slow and took minutes to open, where between physical machines, it took
> seconds.
> I was initialy stuck with this issue, searching in the guest OS & in the
> software configuration for some answers. After some check, I noticed that
> the speed was of 8 Mbps (oh oh).
> At that point, I decided to change the adapter types and when both VMs had
> the Intel 1000T desktop, it was a revelation. The program now opened in
> seconds !
>
>  I have finally been around to do some proper speed tests, and they might
> not be concluant as such and I will let you, devs especially, decide.
> To perform the tests, I have setup 2 Win7 64 bits VMs with 3 adapters each.
> Virtualbox version is 4.2.8, on Debian Wheezy with Testing repos.
>
>  Each VM adapater was only left with IPv4 enabled, everything disabled.
> Static IP were used & NetBios disabled, no other config was changed.
>
>  VM 1 has the following :
>  NIC 1:           MAC: 080027DE6FE9, Attachment: Internal Network
> 'virtio2virtio', Cable connected: on, Trace: off (file: none), Type:
> virtio, Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny,
> Bandwidth group: none
> NIC 2:           MAC: 0800274EBA58, Attachment: Internal Network
> 'virtio2intel', Cable connected: on, Trace: off (file: none), Type: virtio,
> Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny, Bandwidth
> group: none
> NIC 3:           MAC: 080027C92821, Attachment: Internal Network
> 'intel2intel', Cable connected: on, Trace: off (file: none), Type: 82540EM,
> Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny, Bandwidth
> group: none
>
>  VM 2 has the following :
>  NIC 1:           MAC: 08002780E65C, Attachment: Internal Network
> 'virtio2virtio', Cable connected: on, Trace: off (file: none), Type:
> virtio, Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny,
> Bandwidth group: none
> NIC 2:           MAC: 080027009399, Attachment: Internal Network
> 'virtio2intel', Cable connected: on, Trace: off (file: none), Type:
> 82540EM, Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny,
> Bandwidth group: none
> NIC 3:           MAC: 080027592203, Attachment: Internal Network
> 'intel2intel', Cable connected: on, Trace: off (file: none), Type: 82540EM,
> Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny, Bandwidth
> group: none
>
>  The idea is to have 3 networks :
> - the first with each VM with VirtIO
> - the 2nd with only one VirtIO and the 82540EM
> - the last with only 82540EM.
>
>  Following IPs were given :
> virtio2virtio - 10.0.0.1/24 - 10.0.0.2/24
>  virtio2intel - 10.0.1.1/24 - 10.0.1.2/24
>  intel2intel - 10.0.2.1/24 - 10.0.2.2/24
>
>  Finally, I've run iperf 3 times with 3 different TCP window (2000,
> 20000, 200000). I have put the results on pastebin to avoid a huge spam :
> http://pastebin.com/niPzc1ep
>
>  To sum it up :
> - virtio2virtio is capped at 8 Mbps average for a TCP window of 2000, same
> speed as I saw in my 2 speed issues, has acceptable speed at 20000 but
> slows down at 2000000.
> - virtio2intel gets faster & faster as the window increase but is still
> quite slow from what we could expect (244 Mbps @ 200000)
> - intel2intel is the fastest, I get 875 Mbps @ 20000 and 1,3 Gbps @ 200000
> !
>
>  Am I missing something obvious here? Is it a bug? From the User Manual,
> VirtIO should be fastest, but clearly is not and can cause issues.
> I haven't had time to perform this under a Linux guest but from my
> experience, the issue is the same.
> Please let me know if you need more info on my setup.
>
>  Best regards,
> Max
>
>
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