Re: [Qemu-devel] [RFC v2 0/10] Support Receive-Segment-Offload(RSC) for WHQL test of Window guest

[Wei Xu]

On 02/01/2016 11:23 AM, Jason Wang wrote:
> On 02/01/2016 02:13 AM, address@hidden wrote:
> > From: Wei Xu <address@hidden>
> >
> > Patch v2 add detailed commit log.
> >
> > This patch is to support WHQL test for Windows guest, while this feature also
> > benifits other guest works as a kernel 'gro' like feature with userspace 
> > implementation.
> > Feature information:
> >    http://msdn.microsoft.com/en-us/library/windows/hardware/jj853324
> >
> > Both IPv4 and IPv6 are supported, though performance with userspace virtio
> > is slow than vhost-net, there is about 30-40 percent performance
> > improvement to userspace virtio, this is done by turning this feature on
> > and disable 'tso' on corresponding tap interface.
> Maybe you can share us with the numbers?
Sure, will paste them in.
> > Test steps:
> > Although this feature is mainly used for window guest, i used linux guest to 
> > help test
> > the feature, to make things simple, i used 3 steps to test the patch as i moved 
> > on.
> > 1. With a tcp socket client/server pair runnig on 2 linux guest, thus i can 
> > control
> > the traffic and debugging the code as i want.
> > 2. Netperf on linux guest test the throughput.
> > 3. WHQL test with 2 Windows guest.
> >
> > Current status:
> > IPv4 pass all the above tests.
> > IPv6 just passed test step 1 and 2 as described ahead, the virtio nic cannot 
> > receive
> > any packet in WHQL test, debugging on the host side shows all the packets have 
> > been
> > pushed to th vring, by replacing it with a linux guest, i add 10 extra packets 
> > before
> > sending out the real packet, tcpdump running on guest only capture 6 packets, 
> > don't
> > find out the root cause yet, will continue working on this.
> Maybe you can try dropmonitor [1] in both host and guest to find the
> reason of packet dropping.
>
> [1] ./perf script net_dropmonitor
OK, thanks Jason.

Wei
> > Note:
> > A 'MessageDevice' nic chose as 'Realtek' will panic the system sometimes during 
> > setup,
> > this can be figured out by replacing it with an 'e1000' nic.
> >
> > Pending issues & Todo list:
> > 1. Dup ack count not added in the virtio_net_hdr, but WHQL test case passes,
> > looks like a bug in test case.
> > 2. Missing a Feature Bit
> > 3. Missing a few tcp/ip handling
> >      ECN change.
> >      TCP window scale.
> >
> > Wei Xu (10):
> >    virtio-net rsc: Data structure, 'Segment', 'Chain' and 'Status'
> >    virtio-net rsc: Initilize & Cleanup
> >    virtio-net rsc: Chain Lookup, Packet Caching and Framework of IPv4
> >    virtio-net rsc: Detailed IPv4 and General TCP data coalescing
> >    virtio-net rsc: Create timer to drain the packets from the cache pool
> >    virtio-net rsc: IPv4 checksum
> >    virtio-net rsc: Checking TCP flag and drain specific connection
> >      packets
> >    virtio-net rsc: Sanity check & More bypass cases check
> >    virtio-net rsc: Add IPv6 support
> >    virtio-net rsc: Add Receive Segment Coalesce statistics
> >
> >   hw/net/virtio-net.c            | 626 ++++++++++++++++++++++++++++++++++++++++-
> >   include/hw/virtio/virtio-net.h |   1 +
> >   include/hw/virtio/virtio.h     |  65 +++++
> >   3 files changed, 691 insertions(+), 1 deletion(-)