Re: [Qemu-devel] [PATCH 0/5] Add netmap backend offloadings support

[Stefan Hajnoczi <stefanha@gmail.com>]

On Fri, Dec 13, 2013 at 01:04:58PM +0100, Vincenzo Maffione wrote:
> The purpose of this patch series is to add offloadings support
> (TSO/UFO/CSUM) to the netmap network backend, and make it possible
> for the paravirtual network frontends (virtio-net and vmxnet3) to
> use it.
> In order to achieve this, these patches extend the existing
> net.h interface to add abstract operations through which a network
> frontend can manipulate backend offloading features, instead of
> directly calling TAP-specific functions.
> 
> Guest-to-guest performance before this patches for virtio-net + netmap:
> 
>     TCP_STREAM                  5.0 Gbps
>     TCP_RR                      12.7 Gbps
>     UDP_STREAM (64-bytes)       790 Kpps
> 
> Guest-to-guest performance after this patches for virtio-net + netmap:
> 
>     TCP_STREAM                  21.4 Gbps
>     TCP_RR                      12.7 Gbps
>     UDP_STREAM (64-bytes)       790 Kpps
> 
> Experiment details:
>     - Processor: Intel i7-3770K CPU @ 3.50GHz (8 cores)
>     - Memory @ 1333 MHz
>     - Host O.S.: Archlinux with Linux 3.11
>     - Guest O.S.: Archlinux with Linux 3.11
> 
>     - QEMU command line:
>         qemu-system-x86_64 archdisk.qcow -snapshot -enable-kvm -device virtio-net-pci,ioeventfd=on,mac=00:AA:BB:CC:DD:01,netdev=mynet -netdev netmap,ifname=vale0:01,id=mynet -smp 2 -vga std -m 3G
> 
> 
> Vincenzo Maffione (5):
>   net: extend NetClientInfo for offloading manipulations
>   net: TAP uses NetClientInfo offloading callbacks
>   net: virtio-net and vmxnet3 use offloading API
>   net: add offloadings support to netmap backend
>   net: virtio-net and vmxnet3 can use netmap offloadings
> 
>  hw/net/virtio-net.c | 16 +++++---------
>  hw/net/vmxnet3.c    | 12 +++++-----
>  include/net/net.h   | 19 ++++++++++++++++
>  net/net.c           | 55 +++++++++++++++++++++++++++++++++++++++++++++
>  net/netmap.c        | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  net/tap.c           |  6 +++++
>  6 files changed, 154 insertions(+), 18 deletions(-)

Overall I'm happy with the approach.  I left comments about cleaning up
the tap interface that you're moving to NetClient, and about supporting
runtime offload feature toggling.