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

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Date:	Wed, 4 Dec 2013 11:41:34 +0200
From:	Or Gerlitz <or.gerlitz@...il.com>
To:	Joseph Gasparakis <joseph.gasparakis@...el.com>
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	Jerry Chu <hkchu@...gle.com>,
	Or Gerlitz <ogerlitz@...lanox.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Alexei Starovoitov <ast@...mgrid.com>,
	Pravin B Shelar <pshelar@...ira.com>,
	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>
Subject: Re: vxlan/veth performance issues on net.git + latest kernels

On Wed, Dec 4, 2013 at 11:24 AM, Joseph Gasparakis
<joseph.gasparakis@...el.com> wrote:
> On Wed, 4 Dec 2013, Or Gerlitz wrote:

>> nope! with the latest net tree, after handle_offloads is called in
>> vxlan_xmit_skb and before iptunnel_xmit is invoked,
>> skb_shinfo(skb)->gso_type is either 0 or 0x201 which is
>> (SKB_GSO_UDP_TUNNEL | SKB_GSO_TCPV4) and its the same value whether
>> the session runs over veth device or directly over the bridge, where
>> over veth and > 1 stream we see drops, bad perf, etc.
>> I am very interested in the VM case too, so will check it out and let you know.

> Ok, I was really hoping that would be the same...

So when running traffic from VM I do see SKB_GSO_DODGY bit being set!
my environment for
running VMs with sane peformance was screwed  a bit, I will bring it
up later today and see if unsetting the bit helps.


> 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?
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