This message was posted on behalf of Intel Corporation
I understand you are writing a program to calculate latency for PIO write to PCIe based FPGA memory, and you are trying to find out how to ensure that PIO write is completed.
Let me apologize for any inconvenience this issue may be causing to you.
I recommend posting your inquiry on our developer’s forum so they can assist you better. This is the link to it https://software.intel.com/en-us/forum