Merge pull request #11658 from omacom/tcp-bbr-fq

Switch TCP congestion control to BBR with fq pacing

etc/sysctl.d/99-omarchy-sysctl.conf

@@ -1,6 +1,12 @@
 # Solve common flakiness with SSH (MTU discovery on flaky links).
 net.ipv4.tcp_mtu_probing=1
 
+# BBR estimates bottleneck bandwidth and minimum RTT and paces to them, where
+# cubic keeps pushing until packets drop. That cuts queueing latency
+# (bufferbloat) on fast links. fq is the qdisc BBR is built to pace through.
+net.core.default_qdisc=fq
+net.ipv4.tcp_congestion_control=bbr
+
 # Tune reclaim for swap on zram, which is orders of magnitude faster than the
 # disk swapfile these defaults assume.
 

migrations/1789294350.sh

@@ -0,0 +1,11 @@
+echo "Switch TCP congestion control to BBR with fq pacing"
+
+# Boot applies the shipped file regardless; this only makes new connections
+# use BBR now. Setting the sysctls autoloads tcp_bbr and sch_fq. Qdiscs
+# already attached to interfaces stay until they are recreated, normally at
+# reboot.
+if [[ $(sysctl -n net.ipv4.tcp_congestion_control) == "bbr" && $(sysctl -n net.core.default_qdisc) == "fq" ]]; then
+  exit 0
+fi
+
+sudo sysctl -p /etc/sysctl.d/99-omarchy-sysctl.conf >/dev/null || omarchy-state set reboot-required