netdev - Re: [PATCH net-next 0/3] openvswitch: Add STT support.

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Date:	Fri, 23 Jan 2015 13:11:00 -0800
From:	Pravin Shelar <pshelar@...ira.com>
To:	Tom Herbert <therbert@...gle.com>
Cc:	Jesse Gross <jesse@...ira.com>, David Miller <davem@...emloft.net>,
	Linux Netdev List <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 0/3] openvswitch: Add STT support.

On Fri, Jan 23, 2015 at 12:57 PM, Tom Herbert <therbert@...gle.com> wrote:
> On Fri, Jan 23, 2015 at 12:20 PM, Jesse Gross <jesse@...ira.com> wrote:
>> On Fri, Jan 23, 2015 at 10:25 AM, Tom Herbert <therbert@...gle.com> wrote:
>>> On Fri, Jan 23, 2015 at 9:38 AM, Jesse Gross <jesse@...ira.com> wrote:
>>>> On Fri, Jan 23, 2015 at 8:58 AM, Tom Herbert <therbert@...gle.com> wrote:
>>>>> On Tue, Jan 20, 2015 at 12:25 PM, Pravin B Shelar <pshelar@...ira.com> wrote:
>>>>>> Following patch series adds support for Stateless Transport
>>>>>> Tunneling protocol.
>>>>>> STT uses TCP segmentation offload available in most of NIC. On
>>>>>> packet xmit STT driver appends STT header along with TCP header
>>>>>> to the packet. For GSO packet GSO parameters are set according
>>>>>> to tunnel configuration and packet is handed over to networking
>>>>>> stack. This allows use of segmentation offload available in NICs
>>>>>>
>>>>>> Netperf unidirectional test gives ~9.4 Gbits/s performance on 10Gbit
>>>>>> NIC with 1500 byte MTU with two TCP streams.
>>>>>>
>>>>> The reason you're able to get 9.4 Gbit/s with an L2 encapsulation
>>>>> using STT is that it has less protocol overhead per packet when doing
>>>>> segmentation compared to VXLAN (without segmentation STT packets will
>>>>> have more overhead than VXLAN).
>>>>>
>>>>> A VXLAN packet with TCP/IP has headers
>>>>> IP|UDP|VXLAN|Ethernet|IP|TCP+options. Assuming TCP is stuffed with
>>>>> options, this is 20+8+8+16+20+40=112 bytes, or 7.4% MTU. Each STT
>>>>> segment created in GSO, other than the first, has just IP|TCP headers
>>>>> which is 20+20=40 bytes or 2.6% MTU. So this explains throughput
>>>>> differences between VXLAN and STT.
>>>>
>>>> Tom, what performance do you see with a single stream of VXLAN running
>>>> on net-next with default configuration? The difference in numbers
>>>> being posted here is greater than a few percent caused by protocol
>>>> overheard.
>>>
>>> Please look at the data I posted with the VXLAN RCO patches.
>>
>> The data you posted uses 200 streams, so I assume that you are using
>> multiple CPUs. It's not surprising that you would be able to consume a
>> 10G link in that case. STT can do this with a single stream and less
>> than 1 core (or alternately handle higher throughput). Claiming that
>> since both can hit 10G they are same is not accurate.
>>
>> Discussing performance like this seems a little silly given that the
>> code is available. Pravin posted some numbers that he got, if you want
>> to dispute them then why don't you just try running it?
>
> Because you haven't provided network interface like I already
> requested twice, and I really don't have time or motivation to do
> development on your patches or figure out how to do this with OVS. If
> you want me to test your patches re-spin them with a network interface
> included.

I am woking in it. I will have patches by next week.
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