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Date: Thu, 22 Dec 2016 11:15:29 +0000
From: Bruce Richardson <bruce.richardson@intel.com>
To: Royce Niu <royceniu@gmail.com>
Cc: dev@dpdk.org
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Subject: Re: [dpdk-dev] Why IP_PIPELINE is faster than L2FWD
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On Thu, Dec 22, 2016 at 12:18:12AM +0800, Royce Niu wrote:
> Hi all,
> 
> I tested default L2FWD and IP_PIPELINE (pass-through). The throughput of
> IP_PIPELINE is higher immensely.
> 
> There are only two virtual NICs in KVM. The experiment is just moving
> packet from vNIC0  to vNIC1. I think the function is so simple. Why L2FWD
> is much slower?
> 
> How can I improve L2FWD, to make L2FWD faster?
> 
Is IP_PIPELINE in passthrough mode modifying the packets? L2FWD swaps
the mac addresses on each packet as it processes them, which can slow it
down. L2FWD is also more an example of how the APIs work than anything
else. For fastest possible port-to-port forwarding, testpmd should give
the highest performance.

/Bruce