How many maximum different CPU-Cores can be used to processing of one IP-packet?

Question

For example, we have 1 CPU with 8 Cores. How many maximum different CPU-Cores can be used to processing of one IP-packet when it going over Eth0->TCP/IP->App (exclude processing in Application)?

For example, could it be 3 CPU-Cores:

1. Process hardware interrupt
2. Process checksum calculation
3. Process copy kernel-space -> user-space (whose pointer has been sent to the socket)

This is very important for the performance, as each transfer of data between the cores is very expensive.

Answer 1

Generally speaking you'll handle the interrupt on one core, have a chance that the actual kernel work involved in processing it will happen on a different core, and finally hand it off to an application running on a third core. On some OSs you can set process affinity as well as interrupt handler affinity to avoid bouncing your data around.