[Bug 1556980] [NEW] vhost-user: qemu stops processing packets under high load of traffic

[Vincent JARDIN]

Public bug reported:

Already described here,
  https://bugs.launchpad.net/qemu/+bug/1556306

Description of problem:
- qemu socket becomes full, causing qemu to send incomplete
SET_VRING_CALL messages to vhost-user backend (without proper fd set in
ancillary data).
- after some time, some interrupts are lost, causing the VM to stop
transmitting packets.

How reproducible:
Run a stress tests of a vhost-user interface using an UDP
traffic generator. Traffic generator (IXIA) was connected to 2 physical ports that are in turn connected to 2 virtio ports through a linux bridge, VM
(running linux) doing routing to forward packets between the 2 virtio ports.
When traffic reaches high pps rates of small packets,

Actual results:
- VM stop transmitting packets

Expected results:
- VM should never stop transmitting packets

Additional info:
We do propose a fix at:
  http://lists.nongnu.org/archive/html/qemu-devel/2015-12/msg00652.html

for tracking,
  http://git.qemu.org/?p=qemu.git;a=patch;h=5669655aafdb88a8797c74a989dd0c0ebb1349fa

** Affects: qemu-kvm (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: 6wind

** Tags added: 6wind

-- 
You received this bug notification because you are a member of Ubuntu
Server Team, which is subscribed to qemu-kvm in Ubuntu.
https://bugs.launchpad.net/bugs/1556980

Title:
  vhost-user: qemu stops processing packets under high load of traffic

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/1556980/+subscriptions