_Performance Testing issues_

Branch: dpdk-next-net-intel

cf797f58b363f557b3e4a5dfa69ed6dfdc23e6e0 --> performance testing fail

Test environment and result as below:

Ubuntu 18.04
Kernel: 4.15.0-generic
Compiler: gcc 7.4
NIC: Intel Corporation Ethernet Converged Network Adapter 82599ES 10000 Mbps
Target: x86_64-native-linuxapp-gcc
Fail/Total: 2/2

Detail performance results: 
+------------+---------+-------------------------------------+
| frame_size | txd/rxd | throughput difference from expected |
+============+=========+=====================================+
| 64         | 512     | -0.191                              |
+------------+---------+-------------------------------------+
| 64         | 2048    | -1.320                              |
+------------+---------+-------------------------------------+

To view detailed results, visit:
https://lab.dpdk.org/results/dashboard/tarballs/8382/

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