Public bug reported:
It was brought to my attention the following situation:
"""
- Overload not caused by traffic: packet drops with qemu 2.5 are caused
by short (1-2 ms) bursts of packets (1-2k packets) that arrive on the
vswitch at twice the rate at which the external traffic generator sends
them.
- Overload is high enough to fulfill virtio tx queues (256 hard coded
slots <=> 128 packets) run full.
- Fluctuating packet rate: processed packets/ms oscillate storngly over
time:
Avg: ~1020 pkts/ms
Stdev: ~107 ms packets/ms
Min: 720 packets/ms
Max: 1324 packets/ms
Every 2-4 seconds there is a queue overrun (causing rates to go high b/c they
are dropped).
The measures above were taken with a 1 second capture (multiple times)
More information:
- Traffic received back from the QEMU VM is rather oscillating (tx) with peaks
for queue overrun.
- Reverting to QEMU 2.2 the packet drops disappear (no more overload bursts).
- Can't get statistics on QEMU 2.2 (like 2.5) because of instrumentation.
- QEMU 2.3 is also tested and seemed to be fine.
"""
** Affects: qemu (Ubuntu)
Importance: Medium
Assignee: Rafael David Tinoco (inaddy)
Status: In Progress
** Changed in: qemu (Ubuntu)
Importance: Undecided => Medium
** Changed in: qemu (Ubuntu)
Assignee: (unassigned) => Rafael David Tinoco (inaddy)
** Changed in: qemu (Ubuntu)
Status: New => In Progress
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https://bugs.launchpad.net/bugs/1668829
Title:
Performance regression from qemu 2.3 to 2.5 for vhost-user with ovs +
dpdk
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