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

[Stefan Priebe - Profihost AG]

Am 03.01.2018 um 09:14 schrieb 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 ?

complete independend random traffic as it should.

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

inside the guest? where the drop counter stays 0?

auto eth0
iface eth0 inet dhcp

auto eth1
iface eth1 inet static
        address 192.168.0.2
        netmask 255.255.255.0

that's it.

> I'm seeing that you have enable multiqueue on 1 of the interfaces, do you 
> have setup correctly the multiqueue part inside the guest.
uh oh? What is needed inside the guest?

> do you have enough vcpu to handle all the queues ?
Yes.

Stefan

> ----- 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 
>