On 6/7/23 10:05, David Marchand wrote:
On Tue, Jun 6, 2023 at 10:19 AM Maxime Coquelin
<maxime.coque...@redhat.com> wrote:
This series introduces a new type of backend, VDUSE,
to the Vhost library.
VDUSE stands for vDPA device in Userspace, it enables
implementing a Virtio device in userspace and have it
attached to the Kernel vDPA bus.
Once attached to the vDPA bus, it can be used either by
Kernel Virtio drivers, like virtio-net in our case, via
the virtio-vdpa driver. Doing that, the device is visible
to the Kernel networking stack and is exposed to userspace
as a regular netdev.
It can also be exposed to userspace thanks to the
vhost-vdpa driver, via a vhost-vdpa chardev that can be
passed to QEMU or Virtio-user PMD.
While VDUSE support is already available in upstream
Kernel, a couple of patches are required to support
network device type:
https://gitlab.com/mcoquelin/linux/-/tree/vduse_networking_rfc
In order to attach the created VDUSE device to the vDPA
bus, a recent iproute2 version containing the vdpa tool is
required.
Benchmark results:
==================
On this v2, PVP reference benchmark has been run & compared with
Vhost-user.
When doing macswap forwarding in the worload, no difference is seen.
When doing io forwarding in the workload, we see 4% performance
degradation with VDUSE, comapred to Vhost-user/Virtio-user. It is
explained by the use of the IOTLB layer in the Vhost-library when using
VDUSE, whereas Vhost-user/Virtio-user does not make use of it.
Usage:
======
1. Probe required Kernel modules
# modprobe vdpa
# modprobe vduse
# modprobe virtio-vdpa
2. Build (require vduse kernel headers to be available)
# meson build
# ninja -C build
3. Create a VDUSE device (vduse0) using Vhost PMD with
testpmd (with 4 queue pairs in this example)
# ./build/app/dpdk-testpmd --no-pci
--vdev=net_vhost0,iface=/dev/vduse/vduse0,queues=4 --log-level=*:9 -- -i
--txq=4 --rxq=4
9 is a nice but undefined value. 8 is enough.
In general, I prefer "human readable" strings, like *:debug ;-).
4. Attach the VDUSE device to the vDPA bus
# vdpa dev add name vduse0 mgmtdev vduse
=> The virtio-net netdev shows up (eth0 here)
# ip l show eth0
21: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode
DEFAULT group default qlen 1000
link/ether c2:73:ea:a7:68:6d brd ff:ff:ff:ff:ff:ff
5. Start/stop traffic in testpmd
testpmd> start
testpmd> show port stats 0
######################## NIC statistics for port 0 ########################
RX-packets: 11 RX-missed: 0 RX-bytes: 1482
RX-errors: 0
RX-nombuf: 0
TX-packets: 1 TX-errors: 0 TX-bytes: 62
Throughput (since last show)
Rx-pps: 0 Rx-bps: 0
Tx-pps: 0 Tx-bps: 0
############################################################################
testpmd> stop
6. Detach the VDUSE device from the vDPA bus
# vdpa dev del vduse0
7. Quit testpmd
testpmd> quit
Known issues & remaining work:
==============================
- Fix issue in FD manager (still polling while FD has been removed)
- Add Netlink support in Vhost library
- Support device reconnection
-> a temporary patch to support reconnection via a tmpfs file is available,
upstream solution would be in-kernel and is being developed.
->
https://gitlab.com/mcoquelin/dpdk-next-virtio/-/commit/5ad06ce14159a9ce36ee168dd13ef389cec91137
- Support packed ring
- Provide more performance benchmark results
We are missing a reference to the kernel patches required to have
vduse accept net devices.
Right, I mention it in the cover letter, but it should be in the release
note also. I propose to append this to the release note:
"While VDUSE support is already available in upstream Kernel, a couple
of patches are required to support network device type, which are being
upstreamed:
https://lore.kernel.org/all/20230419134329.346825-1-maxime.coque...@redhat.com/";
Does that sound good to you?
Thanks,
Maxime
I had played with the patches at v1 and it was working ok.
I did not review in depth the latest revisions, but I followed your
series from the PoC/start.
Overall, the series lgtm.
For the series,
Acked-by: David Marchand <david.march...@redhat.com>
