[DataPlane] Packet processing pipeline performance analyzis

[GeorgyKirichenko]

It would be nice to see how much time a packet is spending during DataPlane pipeline processing, which could be useful for analyzing performance issues and/or optimizations.

Since the analysis should not result in performance degradation, I would suggest the following approach:

• Create a shared memory segment
• Allocate a dedicated memory block for each worker to avoid interference between them.
• Map the entire block to a sequence of counters initialized to zero.
• Get the TSC counter between each pipeline step we want to analyze.
• Increasing the corresponding counter for each employee by the difference between the TCS counters immediately after and before the analysis stages.

After this we could create a reader application that does:

• Attach to shared memory segment
• Read counters for workers in a loop
• Show the difference between the next and previous values