Optimising Traffic mirroring

[aka320]

1. Avoiding ntohs() operation for every incoming packet

• We read the source and destination port from the packet and change the byte order before doing look-up. We can do this operation while updating the port in the MAP, so that we can avoid it doing for every packet. ntohs() is done twice for every packet.

2. Performing Bitwise operation instead of Modulo

• Even or odd can be identified by doing bitwise & with 1, instead of modulo operation which involves division and getting the reminder i.e requires more operations. (((*ifany) >> (0)) % 2 == 1) is done thrice for every packet if the variable 'ifany' is configured.