Hi, One guest application where this problem is observed is a DPDK application using a pipeline of multiple DPDK logical cores to process packets between Rx from one virtio-net device and Tx to another virtio- net device. The DPDK lcores are coupled through DPDK rings that may buffer a significant amount of packets inside the application.
One possible explanation for the observed changed behavior in Qemu 2.5 compared to Qemu 2.3 could be that for some reason one of these DPDK threads is interrupted so that a significant amount of packets queue up in its ingress ring. These are then forwarded in a burst at larger speed than normal to the Tx virtio queue. This would imply that Qemu 2.5 changes the scheduling of such DPDK threads in the guest. BR, Jan -- 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
