Hi all,
I am using libvirt for more than 10 years, and I have installed
it on lot of servers, with dozens of VMs. Network performances
from VMs to host have always been at top.
But first time I am in front of this problem:
Replacing an old platform made of 2 servers Fedora (36 upgraded to) 37 by 2 servers (H/W stronger) with Fedora 39, same .qcow2 diskimages for VMs, I found out that response times are 2,5 times higher on the new platform than the old one.
I have check H/W, new are better.
I have check standard network configuration, identical, virtio is best (same as older) like I saw in my google searches.
Then I checked network performances:
On old platform, from VM1 to guest:
iperf3
[ ID] Interval
Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 27.7 GBytes 23.8 Gbits/sec 0
sender
[ 5] 0.00-10.00 sec 27.7 GBytes 23.8 Gbits/sec
receiver
On new platform:
[ ID] Interval
Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 2.67 GBytes 2.29 Gbits/sec 17
sender
[ 5] 0.00-10.00 sec 2.67 GBytes 2.29 Gbits/sec
receiver
So intrinsic network performances are ten times better on
old platform.
All VMs network definitions are identical:
<interface type='network'>
<mac address='52:54:xx:yy:zz:53'/>
<source network='default'/>
<model type='virtio'/>
<address type='pci' domain='0x0000' bus='0x07' slot='0x00'
function='0x0'/>
</interface>
On the host:
<network>
<name>default</name>
<uuid>cfcfeeb6-3aa2-4732-9ca4-caf5b6554f2a</uuid>
<forward mode='nat'/>
<bridge name='virbr0' stp='on' delay='0'/>
<mac address='52:54:00:82:33:0c'/>
<ip address='10.0.10.1' netmask='255.255.255.0'>
<dhcp>
<range start='10.0.10.170' end='10.0.10.195'/>
</dhcp>
</ip>
</network>
chatGPT has no clue too.
May I have some help?
Thx
Patrick
