Re: [Qemu-devel] dropped pkts with Qemu on tap interace (RX)

[Alexandre DERUMIER]

Hi Stefan,

>>The tap devices on the target vm shows dropped RX packages on BOTH tap 
>>interfaces - strangely with the same amount of pkts? 

that's strange indeed. 
if you tcpdump tap interfaces, do you see incoming traffic only on 1 interface, 
or both random ?

(can you provide the network configuration in the guest for both interfaces ?)


I'm seeing that you have enable multiqueue on 1 of the interfaces, do you have 
setup correctly the multiqueue part inside the guest.
do you have enough vcpu to handle all the queues ?


----- Mail original -----
De: "Stefan Priebe, Profihost AG" <address@hidden>
À: "qemu-devel" <address@hidden>
Envoyé: Mardi 2 Janvier 2018 12:17:29
Objet: [Qemu-devel] dropped pkts with Qemu on tap interace (RX)

Hello, 

currently i'm trying to fix a problem where we have "random" missing 
packets. 

We're doing an ssh connect from machine a to machine b every 5 minutes 
via rsync and ssh. 

Sometimes it happens that we get this cron message: 
"Connection to 192.168.0.2 closed by remote host. 
rsync: connection unexpectedly closed (0 bytes received so far) [sender] 
rsync error: unexplained error (code 255) at io.c(226) [sender=3.1.2] 
ssh: connect to host 192.168.0.2 port 22: Connection refused" 

The tap devices on the target vm shows dropped RX packages on BOTH tap 
interfaces - strangely with the same amount of pkts? 

# ifconfig tap317i0; ifconfig tap317i1 
tap317i0 Link encap:Ethernet HWaddr 6e:cb:65:94:bb:bf 
UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 
RX packets:2238445 errors:0 dropped:13159 overruns:0 frame:0 
TX packets:9655853 errors:0 dropped:0 overruns:0 carrier:0 
collisions:0 txqueuelen:1000 
RX bytes:177991267 (169.7 MiB) TX bytes:910412749 (868.2 MiB) 

tap317i1 Link encap:Ethernet HWaddr 96:f8:b5:d0:9a:07 
UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 
RX packets:1516085 errors:0 dropped:13159 overruns:0 frame:0 
TX packets:1446964 errors:0 dropped:0 overruns:0 carrier:0 
collisions:0 txqueuelen:1000 
RX bytes:1597564313 (1.4 GiB) TX bytes:3517734365 (3.2 GiB) 

Any ideas how to inspect this issue? 

Greets, 
Stefan