Nemrég került a kernelbe a zero-copy TCP küldés, most pedig sikerült megoldaniuk a fogadási oldalt is.
In the performance-conscious world of high-speed networking, anything that can be done to avoid copying packet data is welcome. The MSG_ZEROCOPY feature added in 4.14 enables zero-copy transmission of data, but does not address the receive side of the equation. It now appears that the 4.18 kernel will include a zero-copy receive mechanism by Eric Dumazet to close that gap, at least for some relatively specialized applications.
Packet reception starts in the kernel with the allocation of a series of buffers to hold packets as they come out of the network interface. As a general rule, the kernel has no idea what will show up next from the interface, so it cannot know in advance who the intended recipient of the next packet to arrive in a given buffer will be. An implementation of zero-copy reception will thus have to map these packet buffers into user-space memory after the packets come in and are associated with an open socket.
Továbbiak: https://lwn.net/Articles/752188/
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