Re: [PATCH 6/6] examples/vhost: add an option to enable Tx zero copy

On Tue, Aug 23, 2016 at 11:31:08AM +0200, Thomas Monjalon wrote:

2016-08-23 16:10, Yuanhan Liu:

quoted

One thing worth noting while using Tx zero copy is the nb_tx_desc has
to be small enough so that the eth driver will hit the mbuf free
threshold easily and thus free mbuf more frequently.

The reason behind that is, when Tx zero copy is enabled, guest Tx used
vring will be updated only when corresponding mbuf is freed. If mbuf is
not freed frequently, the guest Tx vring could be starved.

I think you should explain this behaviour in the doc of the vhost flag.

Agreed. Will do it in v2.

	--yliu