Fast UDP I/O for Firefox in Rust

Original Article ↗ Hacker News Discussion ↗

Debugging & Real‑World Networking Quirks

  • Commenters relate to the article’s “buy the same laptop” debugging story; networking bugs are seen as notoriously hardware‑ and NIC‑specific.
  • Mentions of UDP checksum offload oddities (e.g., 0x0000/0xFFFF meanings) and “mystery packet runts” reinforce how driver/NIC behavior can obscure bugs.
  • One commenter warns that high‑rate UDP/QUIC can effectively DoS smaller hosts and LANs, which is why many networks aggressively rate‑limit or drop UDP.

APIs, GSO/GRO, and Zero‑Copy

  • Some are surprised the article focuses on sendmmsg/recvmmsg, calling them “old” and expecting io_uring instead.
  • Others respond that io_uring doesn’t have a true multi‑datagram equivalent; GSO/GRO is still the main path, and some kernel developers would like to deprecate sendmmsg/recvmmsg.
  • Zero‑copy RX/TX (e.g., Linux msg_zerocopy, RDMA, AF_XDP, userspace NIC drivers) is discussed as promising but complex, hardware‑dependent, and less suitable for browsers due to loss of OS‑level control.
  • Windows/macOS GSO/GRO analogues exist but are described as buggy, raising questions about OS vendor priorities for high‑performance networking.

Performance Gains & Limits

  • The headline result noticed by readers: CPU‑bound throughput jumped from <1 Gbit/s to ~4 Gbit/s; CPU time now mostly in syscalls and crypto.
  • Many see this as a big practical win for laptops/mobile (better efficiency).
  • Others argue 4 Gbit/s is not “fast” relative to what modern CPUs and memory copies can achieve, suggesting 10–20× potential remains untapped due to protocol, API, and kernel design constraints rather than Firefox’s code.
  • There is an extended subthread debating how expensive syscalls actually are on modern CPUs, with conflicting measurements (tens vs hundreds of nanoseconds) and no clear consensus.

QUIC, HTTP/3, and Certificates

  • A question arises whether the new Rust QUIC/UDP stack allows re‑enabling HTTP/3 over self‑signed certs.
  • Multiple replies emphasize this is a policy choice, not a technical limitation or library issue: browsers intentionally make unverifiable HTTPS hard to use to preserve the security model.
  • Critics argue this harms local‑device scenarios and that “TOFU”/self‑signed encryption still usefully protects against passive surveillance; others counter that users must not be allowed to “pretend” such connections are secure.
  • Private PKIs and reverse proxies are proposed as workarounds, but are seen as too complex for nontechnical users.

Project Collaboration & Mozilla

  • The article credits building on the Quinn UDP library; commenters ask whether financial sponsorship accompanies that, noting that contributions so far have mainly been code.
  • This triggers a side discussion on Mozilla’s finances and priorities (executive pay vs. OSS sponsorship), with skepticism that “Mozilla has no money.”

Miscellaneous

  • Readers praise the article’s clear, technical style and wish more Mozilla communication looked like this.
  • There is clarification that Firefox’s minimum Android version has recently been raised, reducing legacy constraints.
  • Some users still report HTTP/3/QUIC issues with specific providers and are pointed to Bugzilla for reproduction help.
  • Brief curiosity about whether this groundwork might eventually enable browser‑native BitTorrent over UDP.