On 27.09.2013 11:03, Patrick Herzfeld wrote:
Hi
I'm currenty testing network QoS implementations stumbled upon quite
strange results when using QoS definitions inside the virtdomain xml.
I'm testing bandwidth from a virtdomain towards a hardware server
connected to the same switch, both connected to gigabit ports. Iperf
tells me the bandwidth is around 939 Mbit/s.
I added this to my virtdomains xml:
<bandwidth>
<inbound average='1280'/>
<outbound average='1280'/>
</bandwidth>
This should limit the bandwidth to around 10 megabit/s 1280 kilobytes/s,
however i get only around 5.14 Mbits/sec...
Has anyone an idea what causes this difference?
I already checked the applied qdisc & class:
root@testvirt-patrick:~ # tc qdisc sh dev vnet1
qdisc htb 1: root refcnt 2 r2q 10 default 1 direct_packets_stat 0
qdisc ingress ffff: parent ffff:fff1 ----------------
SFQ is missing. So I assume you're using and older libvirt (pre 1.0.1).
There has been some bugs prior that release ...
root@testvirt-patrick:~ # tc class sh dev vnet1
class htb 1:1 root prio 0 rate 10240Kbit ceil 10240Kbit burst 1598b
cburst 1598b
.. notably in setting these burst and cburst values.
Try to update and the problem should get resolved.
Michal