Re: [PATCHv3 net-next 0/8] enable/disable zero copy tx dynamically

From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Thu, 1 Nov 2012 21:16:17 +0200

tun supports zero copy transmit since 0690899b4d4501b3505be069b9a687e68ccbe15b,
however you can only enable this mode if you know your workload does not
trigger heavy guest to host/host to guest traffic - otherwise you
get a (minor) performance regression.
This patchset addresses this problem by notifying the owner
device when callback is invoked because of a data copy.
This makes it possible to detect whether zero copy is appropriate
dynamically: we start in zero copy mode, when we detect
data copied we disable zero copy for a while.

With this patch applied, I get the same performance for
guest to host and guest to guest both with and without zero copy tx.

Series applied, thanks Michael.