BPFTUNE(8)

okay so bestie, sit down, hydrate, because we're about to talk about bpftune — that's BPFTUNE(8), from the System Manager's Manual, and she is that girl. auto-tuning your Linux kernel parameters via BPF?? in this economy?? yes. ✨

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🎀 NAME 🎀

BPFTUNE — the tool for auto-tuning of Linux kernel parameters via BPF. periodt. 💅

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🌸 SYNOPSIS 🌸

bpftune [OPTIONS]

OPTIONS := { { -V | --version } | { -h | --help } | { [-s | --stderr
} | { [-c | --cgroup] cgroup} | { [-l | --libdir ] libdir} | [{ -d |
--debug }] } { [-r | --learning_rate ] learning_rate} { [-R |
--rollback ]} { [-S | --support ]} { [-p | --port ] port} { [-q |
--query] query}

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💖 DESCRIPTION 💖

okay so here's the vibe: bpftune ships a whole set of "tuners" — for sysctl parameters, congestion control algorithms, etc. — and their whole job is to optimize performance and stop your system from imposing unnecessary limits on tunables. no cap. 🔥

ngl there's a permissions requirement though: bpftune needs CAP_BPF and CAP_TRACING capabilities, or CAP_SYS_ADMIN on older systemes. it's run via a systemd service, but bestie it can also be run standalone if required. 🫶

want to know if your system even supports the BPF features bpftune needs? run bpftune -S. that's the vibe check right there.

so basic bptune support requires BPF ring buffer, BPF hashmap, and BPF sock ops and k[ret]probe support. on more modern systems, BPF tracing programs and BPF iterators are used instead. individual tuners support legacy mode operation where possible. and for per-network-namespace tuning? you need netns cookie support — without that, only global tuning is supported. tragic but true. 😭

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✨ OPTIONS ✨

• -h, --help — Show help information 💜
• -V, --version — Show version. ✨
• -d, --debug — Show debug output. 🐛
• -a, --allow — Allow tuner only, e.g. foo.so . multiple -a options can be supplied to allow specific tuners. used for testing. 🧪
• -c, --cgroup — Filter events for cgroup. 🫧
• -D, --daemon — Run in daemon mode. 👑
• -s, --stderr — Log to standard error instead of syslog. 📢
• -S, --support — Scan system to see what level of bpftune support is present. 🔍
• -l, --libdir — bptune extra plugin directory; defaults to /usr/local/lib64/bpftune . both /usr/lib64/bpftune and /usr/local/lib64/bpftune can be used to install plugin tuners; if an alternative to /usr/local/lib64/bpftune is wanted, it must be specified via library path. 📂
• -r, --learning_rate — Specify learning rate; supported values range from
  • 0: tunables are changed by/within 1.0625 % of limit
  • 1: tunables are changed by/within 3.125 % of limit
  • 2: tunables are changed by/within 6.25 % of limit
  • 3: tunables are changed by/within 12.5 % of limit
  • 4: tunables are changed by/within 25 % of limit
  • so for example at rate 4, if we are within 25 % of a limit, the limit is increased by 25 %. default learning rate is 4. lower values are more conservative as they change only when closer to limits, but may require more frequent changes as a result. 🧠
• -R, --rollback — Roll back sysctl settings on exit; this allows us to explore tunable updates bpftune makes without making long-term changes to the system. on exit, bpftune summarizes the changes made and rolls back to the sysctl values that were set prior to bpftune running. ↩️
• -p, --port — TCP port to listen on for queries. if not specified, use an ephemeral localhost port. 🚪
• -q, --query — Query bpftune. supported queries include
  • help — show supported queries
  • summary — show summary of changes made by tuners
  • tuners — show loaded tuners and their state
  • tunables — show supported tunables for loaded tuners
  • jtunables — show supported tunables in json format
  • status — show current status of tunables
  • jstatus — show current status of tunables in json format
  • rollback — show changes needed to roll back bpftune changes

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🦋 SEE ALSO 🦋

bpf(2), bpftune(8), 🌈

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fr fr that's the whole page — nothing skipped, nothing invented, all facts intact and all flags accounted for. if you skipped the boring-looking bits, bestie, go back, the tunables are counting on you. 💀

and that's a wrap on BPFTUNE(8) from the System Manager's Manual, page tag BPFTUNE(8) — if you're reading a version of this with a date stamped on it, that's the one, and she ate. 🎀✨🫶