Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

Sign In Register

Quick Links


Shells Virtual Desktop
BMail.ag - Secure Email Service
Server.net
CPLicense.net
VPS Server
Buy VPN
Vultr
VMs for AI
HostDare
HostDare
ReliableSite White-Label Dedicated Hosting for Resellers
InterServer VPS
BMail.ag - Secure Email Service
Best VPN
High-Performance Bare Metal Server Solutions
Karvl.com
Server Mania Cloud Hosting
DataWagon Hosting
AlphaVPS Hosting
Evoxt.com
Clouvider
VPS Hosting with NVMe
Residential IPs in the US & 4G Mobile Proxies in EU & US with Unlimited Bandwidth
ReliableSite White-Label Dedicated Hosting for Resellers
Rabisu - Hosting Solutions
Shells Virtual Desktop

Categories

In this Discussion

Home › Help
New on LowEndTalk? Please Register and read our Community Rules.

All new Registrations are manually reviewed and approved, so a short delay after registration may occur before your account becomes active.

Packet drops on KVM guest

BochiBochi Member
in Help

Hey guys,

got aware of this rather strange behaviour of a KVM guest this day:

In plain words:
There seems to be a pretty constant drop rate on my bridged network interface of the KVM guest,
but on the host node everything seems fine.
Tried to ping for a few minutes and used the service provided by this box -> no problems.
I found some bug reports online regarding a similiar problem, but that dated back a few years and where related to an older kernel version...

Maybe this is a rather common problem and I am just to inexperienced - do you have any suggestions?

Regards, Bochi

Comments

  • yourserverseyourserverse Member
    1. Check your host's irq balancing - maybe all the interrupts happen on a single overloaded core
    2. Check libvirt's config for traffic shaping
    3. Make sure you don't have any tc rules set up
    4. Check your guest's interface load / pps to make sure there is no flooding
    Thanked by 1Bochi
  • BochiBochi Member
    edited July 2015

    @yourserverse said:
    1. Check your host's irq balancing - maybe all the interrupts happen on a single overloaded core

    root@node01:~# grep eth /proc/interrupts
 48:    5016262          0          0          0   PCI-MSI-edge      eth0

    All interrupts are handled by one core, but that should be fine - affinity is set accordingly.
    And load on the systems (node and guest) is well below 0.1, so this shouldn't be a problem.

    1. Check libvirt's config for traffic shaping

    There should be no QoS in place, checked the guest's XML.

    1. Make sure you don't have any tc rules set up
    root@guest:~$ tc qdisc show
qdisc pfifo_fast 0: dev eth0 root refcnt 2 bands 3 priomap  1 2 2 2 1 2 0 0 1 1                   1 1 1 1 1 1

    Seems alright to me, same on host.

    1. Check your guest's interface load / pps to make sure there is no flooding
    root@guest:~/scripts$ ./show_pps.sh eth0
TX eth0: 6 pkts/s RX eth0: 10 pkts/s
TX eth0: 10 pkts/s RX eth0: 10 pkts/s
TX eth0: 8 pkts/s RX eth0: 11 pkts/s
TX eth0: 8 pkts/s RX eth0: 10 pkts/s
TX eth0: 9 pkts/s RX eth0: 13 pkts/s
TX eth0: 7 pkts/s RX eth0: 10 pkts/s
TX eth0: 2 pkts/s RX eth0: 3 pkts/s

    Guest is mostly idling, but checked that too: no flooding...

    Thank you very much for your effort so far! :)

    Thanked by 1yourserverse
  • BochiBochi Member

    Checked the actual ratio and it seems to be quite low:

    vmbr0     Link encap:Ethernet  HWaddr xx:xx:xx:xx:xx:xx
          inet addr:xxx.xxx.xxx.xxx  Bcast:xxx.xxx.xxx.xxx  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:5007634 errors:0 dropped:484 overruns:0 frame:0
          TX packets:501751 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:860548456 (860.5 MB)  TX bytes:65380152 (65.3 MB)

    But nevertheless it somehow annoys me. :P
    Especially as long as I don't know the reason for this... Any other suggestions?

Sign In or Register to comment.