netdev - Re: TCP stalls with 802.3ad + bridge + kvm guest

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Message-ID: <20120811112840.0dc9ba71@nehalam.linuxnetplumber.net>
Date:	Sat, 11 Aug 2012 11:28:40 -0700
From:	Stephen Hemminger <shemminger@...tta.com>
To:	Peter Samuelson <psamuelson@...lder.net>
Cc:	Jesse Brandeburg <jesse.brandeburg@...il.com>,
	Jay Vosburgh <fubar@...ibm.com>, netdev@...r.kernel.org,
	jgoerzen@...lder.net
Subject: Re: TCP stalls with 802.3ad + bridge + kvm guest

On Sat, 4 Aug 2012 17:45:11 -0500
Peter Samuelson <psamuelson@...lder.net> wrote:

> 
> > [Jesse Brandeburg]
> > > try
> > > # ethtool -K ethx tso off gso off lro off
> 
> Specifically, 'lro off' is the trick.  The others don't have a
> noticeable effect.  Now I can get 70 MB/s or better most of the time,
> in either direction.
> 
> Thanks again,
> Peter

When device is added to bridge, the bridge code does ask the device
to turn LRO off (automatically). Unfortunately some device drivers are
broken.
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