[tor-relays] inet_csk_bind_conflict

[Christopher Sheats]

Hello tor-relays,

We are using Ubuntu server currently for our exit relays. Occasionally, exit throughput will drop from ~4Gbps down to ~200Mbps and the only observable data point that we have is a significant increase in inet_csk_bind_conflict, as seen via 'perf top', where it will hit 85% [kernel] utilization.

A while back we thought we solved with with two /etc/sysctl.conf settings:
net.ipv4.ip_local_port_range = 1024 65535
net.ipv4.tcp_tw_reuse = 1

However we are still experiencing this problem.

Both of our (currently, two) relay servers suffer from the same problem, at the same time. They are AMD Epyc 7402P bare-metal servers each with 96GB RAM, each has 20 exit relays on them. This issue persists after upgrading to 0.4.7.11.

Screenshots of perf top are shared here: https://digitalcourage.social/@EmeraldOnion/109440197076214023

Does anyone have experience troubleshooting and/or fixing this problem?

Cheers,

--
Christopher Sheats (yawnbox)
Executive Director
Emerald Onion
Signal: +1 206.739.3390
Website: https://emeraldonion.org/
Mastodon: https://digitalcourage.social/@EmeraldOnion/




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