BPFTUNE-UDP-BUFFER(8)

✨ NAME ✨

bpftune-udp-buffer — it's the bpftune plugin for UDP, and its whole lil job is keeping your UDP buffer sizes and memory limits from ruining the vibe 💅

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💖 DESCRIPTION 💖

okay so bestie, listen. For UDP — literally just like TCP — there's a triple of min, pressure, max that represents the UDP memory limits, and it lives right here:

net.ipv4.udp_mem

If a receive fails with -ENOBUFS, that's the signal that we're hitting those memory limits. So we adaptively bump up pressure and max to make sure memory exhaustion does not occur — as long as we don't get anywhere near actual real memory exhaustion. 👑

But! As memory exhaustion gets approached and we can't increase the overall memory limits anymore, we instead reduce net.core.rmem* values to limit socket memory overheads. Gotta do what you gotta do. 🫶

Now for the UDP receive buffer memory: if a socket is experiencing receive buffer drops within range of the rmem_max_value, we bump net.core.rmem_max. Similarly, we bump rmem_default if sockets are within range of it and they don't have a locked value (locked meaning set via setsockopt). no cap 💅

🎀 Tunables 🎀

• net.ipv4.udp_mem — the min, pressure, max UDP memory, the whole trio ✨
• net.core.rmem_max — the max rcvbuf size you can specify via setsockopt()
• net.core.rmem_default — the default rcvbuf size for when none was set 🙈

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🦋 SEE ALSO 🦋

bpf(2), bpftune(8)

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and that's the whole page, bestie — this one's from the System Manager's Manual, BPFTUNE-UDP-BUFFER(8), and yeah the footer's just the name again, iconic minimalism honestly 💜🧚