测试出现下面的情况，是因为PL端的FIFO之类设置的比较小导致的。
./axidma_benchmark
AXI DMA Benchmark Parameters:
Transmit Buffer Size: 7.91 Mb
Receive Buffer Size: 7.91 Mb
Number of DMA Transfers: 1000 transfers

Using transmit channel 0 and receive channel 1.
Warning: 99.95% of the receive buffer matches the initialization pattern.
This may mean that the receive buffer was not properly updated.
Single transfer test successfully completed!
Beginning performance analysis of the DMA engine.

DMA Timing Statistics:
Elapsed Time: 0.08 s
Transmit Throughput: 104316.99 Mb/s
Receive Throughput: 104316.99 Mb/s
Total Throughput: 208633.97 Mb/s