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

From: Jason Wang
Subject: Re: [Qemu-devel] [ Patch 0/2] Support Receive-Segment-Offload(RSC) for WHQL test of Window guest
Date: Fri, 18 Mar 2016 13:21:41 +0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1

On 03/18/2016 12:24 PM, Wei Xu wrote:
> On 2016年03月18日 10:22, Jason Wang wrote:
>> On 03/18/2016 12:57 AM, Wei Xu wrote:
>>> On 2016年03月17日 23:44, Michael S. Tsirkin wrote:
>>>> On Thu, Mar 17, 2016 at 11:21:28PM +0800, Wei Xu wrote:
>>>>> On 2016年03月17日 14:47, Jason Wang wrote:
>>>>>> On 03/15/2016 05:17 PM,address@hidden  wrote:
>>>>>>> From: Wei Xu<address@hidden>
>>>>>>> Fixed issues based on rfc patch v2:
>>>>>>> 1. Removed big param list, replace it with 'NetRscUnit'
>>>>>>> 2. Different virtio header size
>>>>>>> 3. Modify callback function to direct call.
>>>>>>> 4. Needn't check the failure of g_malloc()
>>>>>>> 5. Other code format adjustment, macro naming, etc
>>>>>>> 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 1x to 3x 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.
>>>>>>> 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.
>>>>>>> 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, looks like the test traffic is
>>>>>>> not sent from
>>>>>>> on the support machine, test device can access both host and
>>>>>>> another linux
>>>>>>> guest, tried a lot of ways to work it out but failed, maybe debug
>>>>>>> from windows
>>>>>>> guest driver side can help figuring it out.
>>>>>> I think you need figure out where was the packet dropped first.
>>>>>> If the
>>>>>> packet was not dropped by windows guest, you may want to try
>>>>>> dropmonitor.
>>>>> Yes, there is something wrong with my previous description, i add
>>>>> some debug
>>>>> code and did new test, the packets are received by
>>>>> virtio_net_receive() and
>>>>> are finished putting to the vring with no error and sent to win guest
>>>>> already, but wireshark on win guest doesn't get it, because the test
>>>>> case
>>>>> did some hacking on the filter, it installed another lightweight
>>>>> filter, i'm
>>>>> not sure how these packets go in the guest, maybe they are
>>>>> received but
>>>>> dropped by driver or stack, etc.
>>>> Add some debug output in the driver, rebuild it and see packets
>>>> as they are received and passed up the stack.
>>> Yes, but this is to win guest, i tried to build a windows debug binary
>>> but failed, is there any possible missing path in virtio between
>>> pushed it to vring and notified the guest successfully? i'm sure at
>>> this by debugging it with gdb.
>> Is the packet always dropped or does it help if you turn off some
>> configuration (e.g checksum offloads) works?
> Yes, only the test packets are dropped, there is no checksum for ipv6
> header,
> i remembered i disabled checksum offloads and changed other features(RSS)
> in the guest but it doesn't help, is there any other tunable values
> for qemu? 

-device virtio-net-pci,? can gives you all the properties.

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