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

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Date:	Fri, 6 Dec 2013 02:30:54 -0800 (PST)
From:	Joseph Gasparakis <joseph.gasparakis@...el.com>
To:	Or Gerlitz <ogerlitz@...lanox.com>
cc:	Joseph Gasparakis <joseph.gasparakis@...el.com>,
	Pravin B Shelar <pshelar@...ira.com>,
	Or Gerlitz <or.gerlitz@...il.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>, jeffrey.t.kirsher@...el.com,
	John Fastabend <john.fastabend@...il.com>
Subject: Re: vxlan/veth performance issues on net.git + latest kernels



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...

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

I was running 3.10.6.

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

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

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?

If you unset it, do you recover?

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

> Currently it doesn't converge with 3.12.x or net.git, with veth/vxlan the
> DODGE bit isn't set when looking on the skb in the vxlan xmit time, so there's
> nothing for me to hack there. For VMs without unsetting the bit things don't
> really work, but unsetting it for itself so far didn't get me far performance
> wise.
> 
> BTW guys, I saw the issues with both bridge/openvswitch configuration - seems
> that we might have here somehow large breakage of the system w.r.t vxlan
> traffic for rates that go over few Gbs -- so would love to get feedback of any
> kind from the people that were involved with vxlan over the last months/year.
> 
> Or.
> 
> net.git]# grep -rn  SKB_GSO_DODGY drivers/net/ net/ipv4 net/core
> drivers/net/macvtap.c:585: skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
> drivers/net/tun.c:1135:         skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
> drivers/net/virtio_net.c:497: skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
> drivers/net/xen-netback/netback.c:1146: skb_shinfo(skb)->gso_type |=
> SKB_GSO_DODGY;
> drivers/net/xen-netfront.c:823: skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
> net/ipv4/af_inet.c:1264:                       SKB_GSO_DODGY |
> net/ipv4/tcp_offload.c:56: SKB_GSO_DODGY |
> net/ipv4/gre_offload.c:40: SKB_GSO_DODGY |
> net/ipv4/udp_offload.c:53:              if (unlikely(type & ~(SKB_GSO_UDP |
> SKB_GSO_DODGY |
> net/core/dev.c:2694:            if (shinfo->gso_type & SKB_GSO_DODGY)
> 
> 
> 
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