[libvirt-users] Strange QoS behavior

[Gao Yongwei]

2012/12/4 Davide Guerri <davide.guerri at gmail.com>

> 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?
>

you can use this command to list the filter:
   tc filter list dev vnet43 root
and check the mtu , and also   read this:
http://www.redhat.com/archives/libvir-list/2011-August/msg00333.html
as i know,the libvirt0.9.10 has this problem,while the mtu has been set to
64k in libvirt dev version
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