"Kernel bypass" network adapter - what is this technology?

Question

Computer networks

Hello. It is necessary to reduce system latency at the level of processing TCP/UDP packets. To solve this problem, as I know, network adapters with "kernel bypass" technology are used, when the network card driver works directly with the application, bypassing the operating system kernel. I would like to understand how it looks in practice? Does the application itself need to implement technology support, or will the card driver itself determine which application should give priority to the OS kernel? Is there a problem with drivers for different OS? What side problems can be expected?

Answer 1

man netmap for example. It is just about for these purposes and is used.

Answer 2

"Kernel bypass" can refer to two rather different approaches: the use of special ASICs, which are shifted to the task of processing packets, such as filtering or routing, or technologies when the processing of network packets is completely taken out in userspace. In any case, in addition to hardware support and / or specialized equipment, technology support is required inside the application, and in the second case it is very significant, up to the implementation of its own TCP / IP stack, because all this goes by the system stack. Those. you must understand that you will receive "channel" traffic, and work approximately like through pcap libraries.