Re: Kernel 4.13.0-rc4-next-20170811 - IP Routing / Forwarding performance vs Core/RSS number / HT on

[Paweł Staszewski]

Hi

Are there any plans to have this fix normally in kernel ?

Or it is mostly only hack - not longterm fix and need to be different ?


All tests that was done shows that without this patch there is about 
20-30% network forwarding performance degradation when using vlan 
interfaces


Thanks
Paweł



W dniu 2017-08-15 o 03:17, Eric Dumazet pisze:
On Mon, 2017-08-14 at 18:07 -0700, Eric Dumazet wrote:

Or try to hack the IFF_XMIT_DST_RELEASE flag on the vlan netdev.
Something like :

diff --git a/net/8021q/vlan_netlink.c b/net/8021q/vlan_netlink.c
index 
5e831de3103e2f7092c7fa15534def403bc62fb4..9472de846d5c0960996261cb2843032847fa4bf7
 100644
--- a/net/8021q/vlan_netlink.c
+++ b/net/8021q/vlan_netlink.c
@@ -143,6 +143,7 @@ static int vlan_newlink(struct net *src_net, struct 
net_device *dev,
        vlan->vlan_proto = proto;
        vlan->vlan_id         = nla_get_u16(data[IFLA_VLAN_ID]);
        vlan->real_dev        = real_dev;
+       dev->priv_flags |= (real_dev->priv_flags & IFF_XMIT_DST_RELEASE);
        vlan->flags   = VLAN_FLAG_REORDER_HDR;
  
  	err = vlan_check_real_dev(real_dev, vlan->vlan_proto, vlan->vlan_id);