[libvirt-users] Strange QoS behavior

[Davide Guerri]

Here they are:

!(~) #  tc class show dev vnet43
class htb 1:1 root prio 0 rate 20480Kbit ceil 20480Kbit burst 1597b cburst 1597b 

!(~) #  tc filter show dev vnet43
filter parent 1: protocol ip pref 49152 fw 
filter parent 1: protocol ip pref 49152 fw handle 0x1 classid :1 

!(~) #  tc qdisc show dev vnet43
qdisc htb 1: root refcnt 2 r2q 10 default 1 direct_packets_stat 0
qdisc ingress ffff: parent ffff:fff1 ---------------- 





On 03/dic/2012, at 17:19, Michal Privoznik <mprivozn at redhat.com> wrote:

> On 03.12.2012 16:37, Davide Guerri wrote:
>> Hi,
>> I'm having some weird problem with the setup of the QoS on a bridged network.
>> 
>> As the docs states, outbound/inbound average speed should be expressed in KBps (KBytes per second) but in order to get a maximum speed of 10Mbps (megabits per second) surprising enough I have to use 2560 on the guest (not 1280 as expected).
>> Using 1280 units I get a speed og 5Mbps.
>> 
>> I'm aware of peak and burst parameters but even with them I'm seeing the same (long-term) behavior. 
>> 
>> Here follows my configuration. 
>> 
>> Thank you in advance for any help you can provide.
>> 
>> 
>> 
>> Domain definition (relevant part only)
>> 
>> virsh # dumpxml mydomain
>> <domain type='kvm' id='45'>
>> [...]
>> <devices>
>>  [...]
>>  <interface type='network'>
>>    <mac address='52:54:00:xx:xx:xx'/>
>>    <source network='br909'/>
>>    <target dev='vnet43'/>
>>    <model type='virtio'/>
>>    <bandwidth>
>>      <inbound average='2560'/>
>>      <outbound average='2560'/>
>>    </bandwidth>
>>    <alias name='net0'/>
>>    <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
>>  </interface>
>>  [...]
>> </devices>
>> </domain>
>> 
>> 
>> The network definition:
>> virsh # net-dumpxml br909
>> <network>
>> <name>br909</name>
>> <uuid>07319380-2025-cdcc-924a-149cd0370b56</uuid>
>> <forward mode='bridge'/>
>> <bridge name='br909' />
>> </network>
>> 
>> 
>> And iperf result (client and server are on the same vlan and they are running on the same host)
>> 
>> [  5] local xx.xx.xx.xx port 5001 connected with xx.xx.xx.yy port 18396
>> [  5]  0.0-30.1 sec  35.4 MBytes  9.87 Mbits/sec
> 
> Hm, strange. What does:
> 
>  tc class show dev vnet43
>  tc filter show dev vnet43
>  tc qdisc show dev vnet43
> 
> show?