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Date: Fri, 23 Sep 2016 12:11:26 +0800
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
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Cc: "Xu, Qian Q" <qian.q.xu@intel.com>,
 Maxime Coquelin <maxime.coquelin@redhat.com>
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Subject: Re: [dpdk-dev] [PATCH 0/6] vhost: add Tx zero copy support
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On Mon, Aug 29, 2016 at 08:57:52AM +0000, Xu, Qian Q wrote:
> Btw, some good news: if I run a simple dequeue workload (running rxonly in vhost-pmd and runnin txonly in guest testpmd), it yields ~50% performance boost for packet size 1518B, but this case is without NIC. 
> And similar case as vhost<-->virtio loopback, we can see ~10% performance gains at 1518B without NIC. 
> 
> Some bad news: If with the patch, I noticed a 3%-7% performance drop if zero-copy=0 compared with current DPDK(e.g: 16.07) at vhost/virtio loopback and vhost RX only + virtio TX only. Seems the patch will 
> Impact the zero-copy=0 performance a little. 

There are some follow up discussion internally, the 3%-7% drop reported
by Qian when zero-copy is not enabled is acutally due to the fluctuation.
So, a false alarm.

	--yliu