netdev - Re: vxlan/veth performance issues on net.git + latest kernels

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Date:	Sat, 7 Dec 2013 23:27:25 +0200
From:	Or Gerlitz <or.gerlitz@...il.com>
To:	Joseph Gasparakis <joseph.gasparakis@...el.com>
Cc:	Or Gerlitz <ogerlitz@...lanox.com>,
	Pravin B Shelar <pshelar@...ira.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Jerry Chu <hkchu@...gle.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Alexei Starovoitov <ast@...mgrid.com>,
	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
	John Fastabend <john.fastabend@...il.com>
Subject: Re: vxlan/veth performance issues on net.git + latest kernels

On Fri, Dec 6, 2013, Joseph Gasparakis <joseph.gasparakis@...el.com> wrote:
> On Fri, 6 Dec 2013, Or Gerlitz wrote:
>
>> On 04/12/2013 11:41, Or Gerlitz wrote:
>> > On Wed, Dec 4, 2013 at 11:24 AM, Joseph
>> > Gasparakis<joseph.gasparakis@...el.com>  wrote:
>> > > >And just for the record,
>> > > >you are seeing (SKB_UDP_TUNNEL | SKB_GSO_TCPV4) as 0x201 while I was
>> > > >seeing it as 0x81 because commit 61c1db7fae "ipv6: sit: add GSO/TSO
>> > > >support" pushed the SKB_UDP_TUNNEL two bits left, and I had done my tests
>> > > before it.
>> > indeed, also, on what kernel did you conducted your tests which you managed
>> > to WA the problem with unsetting that bit?
>>
>>
>> Hi Joseph,
>>
>> Really need your response here --
>
> I'm sorry Or, I managed to miss your original request...

sure.. it happens.

>> 1. on which kernel did you manage to get along fine vxlan performance wise
>> with this hack?

> I was running 3.10.6.

I see, will try it out, and just for getting closer to your env, what
kernel where the guests running? was a bridge / ovs instance involved
in the VM PV connectivity?


>> 2. did the hack helped for both veth host traffic or only on PV VM traffic?

> No, just VM. I haven't tried veth.

I see, earlier I was somehow under the impression you noted the
problem for veth too.

> If you leave the DODGY bit, does your traffic get droped on Tx, after it
> leaves vxlan and before it hits your driver, which is what I had seen. Is
> that right?

What I saw is that if I leave the DODGY bit set, practically things
don't work at all, its not that some packets are dropped, was that
what you saw?

Or on your env only **some** or **few** packets were dropped each time
but this killed the tcp session performance?

Also, did you hack/modified the VM NIC MTU to take into the account
the encapsulation overhead?

> If you unset it, do you recover?

let me redo this with your setting and see, please make sure to tell
me what kernel the VM was running too (thanks!)

> What is the output of your ethtool -k on the interface you are
> transmitting from?

will send you tomorrow, but this happens without offloads for
encapsulated traffic.
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