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bpftune-udp-buffer.rst

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BPFTUNE-UDP-BUFFER

UDP buffer bpftune plugin for managing UDP buffer sizes, memory limits

Manual section:8

DESCRIPTION

For UDP - like TCP - a triple of min, pressure, max represents UDP memory limits and is specified in

net.ipv4.udp_mem

If receive fails with -ENOBUFS this indicates memory limits are being reached; we adaptively increase pressure and max to ensure that memory exhaustion does not occur (as long as we do not approach real memory exhaustion). As memory exhaustion is approached and we can no longer increase overall memory limits, reduce net.core.rmem* values to limit socket memory overheads.

For UDP receive buffer memory, bump net.core.rmem_max if a socket experiences receive buffer drops within range of the rmem_max_value. Similarly bump rmem_default if sockets are within range of it and do not have a locked (via setsockopt) value.

Tunables:

  • net.ipv4.udp_mem: min, pressure, max UDP memory
  • net.core.rmem_max: max rcvbuf size specifiable via setsockopt()
  • net.core.rmem_default: default rcvbuf size where none was set