Subject: Re: ixgbe: cannot enable LRO

From: Otto Sabart <[email-masked]>
Date: Fri, 6 May 2016 12:18:58 +0200

> On Wed, Apr 27, 2016 at 2:36 AM, Otto Sabart <[email-masked]> wrote:
> >
> > Hello everyone,
> > does anybody have a problem with LRO on ixge (on latest 4.6-rc5)?
> > I cannot find a way to enable it.
> >
> > On stable RHEL7.2 kernel everything works fine.
> >
> > I opened a bug report [0].
> >
> > [0] https://bugzilla.kernel.org/show_bug.cgi?id=117291
> >
> >
> > Thanks!
> >
> > Ota
> 

Hello Alex,

> So I am able to turn on LRO without any issues.

Yes, I badly desciribed the problem. The LRO was not possible to turn on
immediately _after the boot_ (I was enabling it in /etc/rc.local).

When I reloaded the ixgbe driver, the LRO was possible to turn on
without problem.

I found out that the problem was caused by network manager. When I
disabled NM, the LRO started to work.

> 
> Do you know if you have done anything that might disable LRO such as
> modified the rx-usecs to a value less than 10 or enabled routing or
> bridging on the device?  Also I think a stacked device might be able
> to block you from enabling LRO unless all the devices stacked on the
> interface can support it.

I did not modify rx-usecs (at least not intentionally).  Its value is
always (with disabled or enabled LRO) equal to 1 (with disabled NM).

$ ethtool -c ixgbe | grep rx-usecs
rx-usecs: 1
rx-usecs-irq: 0
rx-usecs-low: 0
rx-usecs-high: 0

There is no linux bridge or routing enabled on this device. There is
only a VLAN configured. Does it matter?

$ ip l show ixgbe
9: ixgbe: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT qlen 1000
    link/ether 00:1b:21:90:c3:86 brd ff:ff:ff:ff:ff:ff

$ ip l show ixgbe.40
19: ixgbe.40@ixgbe: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT qlen 1000
    link/ether 00:1b:21:90:c3:86 brd ff:ff:ff:ff:ff:ff

I updated the bugzilla [0] and I think we can close this as a NOTABUG.

Thanks!

Ota