[znpy]

It may or may not be good, depending on a number of fact.

I did read the original linux zerocopy papers from google for example, and at the time (when using tcp) the juice was worth the squeeze when payload was larger than than 10 kilobytes (or 20? Don’t remember right now and i’m on mobile).

Also a common technique is batching, so you amortise the round-trip time (this used to be the cost of sendmmsg/recvmmsg) over, say, 10 payloads.

So yeah that number alone can mean a lot or it can mean very little.

In my experience people that are doing low latency stuff already built their own thing around msg_zerocopy, io_uring and stuff :)

[hinkley]

io_uring is a tool for maximizing throughput not minimizing latency. So the correct measure is transactions per millisecond not milliseconds per transaction.

Little’s Law applies when the task monopolizes the time of the worker. When it is alternating between IO and compute, it can be off by a factor of two or more. And when it’s only considering IO, things get more muddled still.

[znpy]

> io_uring is a tool for maximizing throughput not minimizing latency.

some features are explicitly designed to minimize latency. I'm thinking of the IORING_SETUP_IOPOLL and IORING_SETUP_SQPOLL flags for io_uring_setup .

I'm not making that up, the manpage says that: https://manpages.debian.org/unstable/liburing-dev/io_uring_s...