Many general-purpose OS abstractions start leaking when you're working on systems-like software.

You notice it when web servers are doing kernel bypass to for zero-copy, low-latency networking, or database engines throw away the kernel's page cache to implement their own file buffer.

Web servers doing kernel bypass for zero-copy networking? Do you have a specific example in mind? I'm curious.

The most common example is DPDK [1]. It's a framework for building bespoke networking stacks that are usable from userspace, without involving the kernel.

You'll find DPDK mentioned a lot in the networking/HPC/data center literature. An example of a backend framework that uses DPDK is the seastar framework [2]. Also, I recently stumbled upon a paper for efficient RPC networks in data centers [3].

If you want to learn more, the p99 conference has tons of speakers talking about some interesting challenges in that space.

[1] https://www.dpdk.org/.

[2] https://github.com/scylladb/seastar

[3] https://github.com/erpc-io/eRPC