Network interface card rate limiting

A programmable network interface controller (NIC) of a network security device comprising:

• a non-transitory storage device having embodied therein instructions representing a processor status monitoring routine and a packet delivery routine;
• and
• one or more processors coupled to the non-transitory storage device and operable to execute the processor status monitoring routine and the packet delivery routine to perform a method comprising:
• receiving data packets from a private network protected by the network security device, wherein the NIC is coupled to a host central processing unit (CPU) of the network security device through a bus;
• monitoring, by the processor status monitoring routine, a status of the host CPU;
• setting, by the processor status monitoring routine, a rate limiting mode indicator based on the status;
• when the rate limiting mode indicator indicates rate limiting is inactive, then causing, by the packet delivery routine, the host CPU to perform one or more high priority tasks in relation to the received data packets within a kernel of an operating system of the host CPU by delivering or making available the received data packets to the host CPU;
• and
• when the rate limiting mode indicator indicates rate limiting is active, then avoiding starving of one or more lower priority tasks of host CPU cycles by, the packet delivery routine, temporarily stopping or slowing said delivering or making available the received data packets to the host CPU.