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 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1668829 Title: Performance regression from qemu 2.3 to 2.5 for vhost-user with ovs + dpdk To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1668829/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs