Re: [PATCH net-next 1/2] tcp: add TCP_ZEROCOPY_RECEIVE support for zerocopy receive

[Eric Dumazet]

On 04/25/2018 09:22 AM, Andy Lutomirski wrote:

> In general, I suspect that the zerocopy receive mechanism will only
> really be a win in single-threaded applications that consume large
> amounts of receive bandwidth on a single TCP socket using lots of
> memory and don't do all that much else.

This was dully noted in the original patch submission.

https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/commit/?id=309c446cb45f6663932c8e6d0754f4ac81d1b5cd

Our intent at Google is to use it for some specific 1MB+ receives, not as a generic and universal mechanism.

The major benefit is really the 4KB+ MTU, allowing to pack exactly 4096 bytes of payload per page.