_Performance Testing issues_

Branch: dpdk-next-eventdev

db8874909a9159b7706c615e778e09050d68b0ae --> 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 XL710-QDA2 40000 Mbps
Target: x86_64-native-linuxapp-gcc
Fail/Total: 2/2

Detail performance results: 
+------------+---------+----------+-------------+------------------------------+
| frame_size | txd/rxd | num_cpus | num_threads |  throughput difference from  |
|            |         |          |             |           expected           |
+============+=========+==========+=============+==============================+
| 64         | 512     | 1        | 1           | -4.6929%                     |
+------------+---------+----------+-------------+------------------------------+
| 64         | 2048    | 1        | 1           | -15.41175%                   |
+------------+---------+----------+-------------+------------------------------+

To view detailed results, visit:
https://lab.dpdk.org/results/dashboard/tarballs/15694/

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