[DragonFlyBSD - Bug #3090] (Closed) VirtIO/vtnet: very poor IPv6 receiving performance (~100x slower)

bugtracker-admin at leaf.dragonflybsd.org bugtracker-admin at leaf.dragonflybsd.org
Wed Mar 14 06:33:01 PDT 2018

Issue #3090 has been updated by liweitianux.

Status changed from In Progress to Closed

The reason for this issue is explained in Bug #3089, so just close this one.

Bug #3090: VirtIO/vtnet: very poor IPv6 receiving performance (~100x slower)

* Author: liweitianux
* Status: Closed
* Priority: Normal
* Assignee: vadaszi
* Category: Networking
* Target version: 

I'm running DFly (4.8.0) on a VPS with both IPv4 and IPv6.  However, I'm suffering poor *IPv6 receiving* performance (~100x slower!!), but IPv6 sending, IPv4 sending and receiving all perform very well.

I carried out several tests, and finally I'm quite sure that the problem exists in DFly's VirtIO driver.

I booted DFly (5.0), FreeBSD (11), and Arch Linux (201705) LiveCDs on my VPS, and configured basic IPv6 connection, then tried to download a 128 MB test file from the VPS provider's service.  The followings are the test results:

OS (virtio) | download speed
DFly (IPv6) | ~80 kB/s (NOTE: it's kB/s)
FBSD (IPv6) | ~85 MB/s
Arch (IPv6) | ~83 MB/s

In addition, I used "iperf3" to further test the sending/receiving bandwidth of my VPS (located in the Netherlands), against a iperf server in France (bouygues.iperf.fr):

OS/driver        | DFly (virtio)  | DFly (em)
IPv4 - sending   | ~240 Mb/s      | ~170 Mb/s
IPv4 - receiving | ~400 Mb/s      | ~430 Mb/s
IPv6 - sending   | ~160 Mb/s      | ~115 Mb/s
IPv6 - receiving | ~0.5 Mb/s (!!) | ~370 Mb/s

To confirm the problem, I switched the network driver of my VPS from "VirtIO" to "Intel PRO/1000" (i.e., "em" driver) and redo the tests, which gave me very impressing IPv6 performance!

NOTE: I did these tests yesterday and today, so the reported network bandwidth might vary much.  But the VirtIO IPv6 receiving problem is very obvious!

I'm not sure whether this problem is due to the maybe out-of-date virtio driver (compared to FreeBSD's), or because it does not well integrate with the DFly system.


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