Re: [Qemu-devel] [ RFC Patch v6 0/2] Support Receive-Segment-Offload(RSC) for WHQL

[Jason Wang <jasowang@redhat.com>]

On 2016年05月29日 00:37, wexu@redhat.com wrote:
> From: Wei Xu <wexu@redhat.com>
>
> Changes in V6:
> - Sync upstream code
> - Split new fields in 'virtio_net_hdr' to a seperate patch
> - Remove feature bit code, replace it with a command line parameter 'guest_rsc'
> which is turned off by default.
>
> Changes in V5:
> - Passed all IPv4/6 test cases
> - Add new fields in 'virtio_net_hdr'
> - Set 'gso_type' & 'coalesced packets' in new field.
> - Bypass all 'tcp option' packet
> - Bypass all 'pure ack' packet
> - Bypass all 'duplicate ack' packet
> - Change 'guest_rsc' feature bit to 'false' by default
> - Feedbacks from v4, typo, etc.

Change-log is very important for the ease and speed up reviewers. More 
details are more than welcomed. But I see some changes were not 
documented here. Please give a more complete one in next iteration.

>
> Note:
> There is still a few pending issues about the feature bit, and need to be
> discussed with windows driver maintainer, so linux guests with this patch
> won't work at current, haven't figure it out yet, but i'm guessing it's
> caused by the 'gso_type' is set to 'VIRTIO_NET_HDR_GSO_TCPV4/6',
> will fix it after get the final solution, the below test steps and
> performance data is based on v4.

This is probably because you've increased the vnet header length.

>
> Another suggestion from Jason is to adjust part of the code to make it
> more readable, since there maybe still few change about the flowchart
> in the future, such as timestamp, duplicate ack, so i'd like to delay it
> temporarily.
>
> Changes in V4:
> - Add new host feature bit
> - Replace using fixed header lenght with dynamic header lenght in VirtIONet
> - Change ip/ip6 header union in NetRscUnit to void* pointer
> - Add macro prefix, adjust code indent, etc.
>
> Changes in V3:
> - Removed big param list, replace it with 'NetRscUnit'
> - Different virtio header size
> - Modify callback function to direct call.
> - Needn't check the failure of g_malloc()
> - Other code format adjustment, macro naming, etc
>
> Changes in 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 1.5x to 2x performance improvement to
> userspace virtio, this is done by turning this feature on and disable
> 'tso/gso/gro' on corresponding tap interface and guest interface, while get
> less improment with all these feature on.
>
> Linux guest performance data(Netperf):
> MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.2.101 () port 0 AF_INET : nodelay
> Size   Size    Size     Time     Throughput
> bytes  bytes   bytes    secs.    10^6bits/sec
>
>   87380  16384     64    6.00     1221.20
>   87380  16384     64    6.00     1260.30
>
>   87380  16384    128    6.00     1978.51
>   87380  16384    128    6.00     2286.05
>
>   87380  16384    256    6.00     2677.94
>   87380  16384    256    6.00     4615.42
>
>   87380  16384    512    6.00     2956.54
>   87380  16384    512    6.00     5356.39
>
>   87380  16384   1024    6.00     2798.17
>   87380  16384   1024    6.00     4943.30
>
>   87380  16384   2048    6.00     2681.09
>   87380  16384   2048    6.00     4835.81
>
>   87380  16384   4096    6.00     3390.14
>   87380  16384   4096    6.00     5391.54
>
>   87380  16384   8092    6.00     3008.27
>   87380  16384   8092    6.00     5381.68
>
>   87380  16384  10240    6.00     2999.89
>   87380  16384  10240    6.00     5393.11
>
> 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 running 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 guests.
>
> Wei Xu (3):
>    virtio-net rsc: support coalescing ipv4 tcp traffic
>    virtio-net rsc: support coalescing ipv6 tcp traffic
>    virtio-net rsc: add 2 new rsc information fields to 'virtio_net_hdr'
>
>   hw/net/virtio-net.c                         | 642 +++++++++++++++++++++++++++-
>   include/hw/virtio/virtio-net.h              |   2 +
>   include/hw/virtio/virtio.h                  |  75 ++++
>   include/standard-headers/linux/virtio_net.h |   3 +
>   4 files changed, 721 insertions(+), 1 deletion(-)
>