I saw this article:
Zero-copy networking will be in 2.4.4. This patch, by David Miller, Alexey Kuznetsov, and others, has been in development and testing for some time, and was incorporated into the "ac" kernel series back in 2.4.2ac4. In a way, it is a surprising change to see in a stable kernel series, since it makes fundamental changes deep in the networking code. From all reports, however, it is solid, and, in certain situations, it should produce significant performance benefits.
Can someone tell me if zero-copy networking exists by default in Linux, or whether this patch was just to allow people who wanted to do zero-copy networking to be able to implement it?
In other words, in the current Ubuntu does it perform zero-copy networking all the time or would I have to use certain system calls to utilise the above patch?