_Performance Testing issues_

Branch: dpdk-next-net

79af6d1336abd6012db15485e7a0a79fa5fd0a15 --> performance testing fail

Test environment and result as below:

Ubuntu 18.04
Kernel: 4.15.0-generic
GCC: 7.4
NIC: Mellanox ConnectX-5 100000 Mbps
Target: x86_64-native-linuxapp-gcc
Fail/Total: 1/6

Detail performance results: 
+------------+---------+-------------------------------------+
| frame_size | txd/rxd | throughput difference from expected |
+============+=========+=====================================+
| 64         | 256     | -4.020                              |
+------------+---------+-------------------------------------+
| 128        | 256     | -0.961                              |
+------------+---------+-------------------------------------+
| 256        | 256     | -0.608                              |
+------------+---------+-------------------------------------+
| 512        | 256     | -0.192                              |
+------------+---------+-------------------------------------+
| 1024       | 256     | -0.062                              |
+------------+---------+-------------------------------------+
| 1518       | 256     | 0.015                               |
+------------+---------+-------------------------------------+

Ubuntu 18.04
Kernel: 4.15.0-generic
GCC: 7.4
NIC: Mellanox ConnectX-4 Lx 40000 Mbps
Target: x86_64-native-linuxapp-gcc
Fail/Total: 3/6

Detail performance results: 
+------------+---------+-------------------------------------+
| frame_size | txd/rxd | throughput difference from expected |
+============+=========+=====================================+
| 64         | 256     | -1.834                              |
+------------+---------+-------------------------------------+
| 128        | 256     | -1.944                              |
+------------+---------+-------------------------------------+
| 256        | 256     | -1.351                              |
+------------+---------+-------------------------------------+
| 512        | 256     | -0.020                              |
+------------+---------+-------------------------------------+
| 1024       | 256     | -0.004                              |
+------------+---------+-------------------------------------+
| 1518       | 256     | 0.010                               |
+------------+---------+-------------------------------------+

Ubuntu 18.04
Kernel: 4.15.0-generic
GCC: 7.4
NIC: Mellanox ConnectX-4 Lx 25000 Mbps
Target: x86_64-native-linuxapp-gcc
Fail/Total: 2/6

Detail performance results: 
+------------+---------+-------------------------------------+
| frame_size | txd/rxd | throughput difference from expected |
+============+=========+=====================================+
| 64         | 256     | -1.270                              |
+------------+---------+-------------------------------------+
| 128        | 256     | -1.350                              |
+------------+---------+-------------------------------------+
| 256        | 256     | 0.005                               |
+------------+---------+-------------------------------------+
| 512        | 256     | 0.001                               |
+------------+---------+-------------------------------------+
| 1024       | 256     | 0.011                               |
+------------+---------+-------------------------------------+
| 1518       | 256     | 0.011                               |
+------------+---------+-------------------------------------+

https://lab.dpdk.org/results/dashboard/tarballs/7073/

UNH-IOL DPDK Performance Test Lab

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