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feat(deploy): host sysctls for UDP buffers + netdev backlog/budget

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99-left4me.conf: rmem_max/wmem_max=8M (with 512K defaults),
netdev_max_backlog=5000, netdev_budget=600, vm.swappiness=10.
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mwiegand 2026-05-09 09:53:07 +02:00
parent 66d83a0282
commit b3fca4772c
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2 changed files with 37 additions and 0 deletions
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21
deploy/files/etc/sysctl.d/99-left4me.conf Normal file
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@ -0,0 +1,21 @@
# Host-side perf baseline for left4me — see
# docs/superpowers/specs/2026-05-09-l4d2-server-host-perf-baseline-design.md
#
# UDP socket buffers: distro defaults of ~128 KiB are too small for sustained
# Source-engine UDP across multiple instances. 8 MiB matches the standard
# 1 Gbit recommendation; rmem_default/wmem_default protect sockets that don't
# explicitly enlarge their buffers.
net.core.rmem_max = 8388608
net.core.wmem_max = 8388608
net.core.rmem_default = 524288
net.core.wmem_default = 524288
# Kernel softirq UDP path: the per-CPU backlog queue starts dropping packets
# at the default 1000 under multi-instance burst; 5000 absorbs realistic peaks.
# netdev_budget = 600 gives softirq more drain headroom per pass.
net.core.netdev_max_backlog = 5000
net.core.netdev_budget = 600
# Latency-sensitive default: avoid swap unless the box is really under
# pressure. Harmless on swapless hosts.
vm.swappiness = 10

16
deploy/tests/test_deploy_artifacts.py
View file

@ -11,6 +11,7 @@ WEB_UNIT = DEPLOY / "files/usr/local/lib/systemd/system/left4me-web.service"
SERVER_UNIT = DEPLOY / "files/usr/local/lib/systemd/system/left4me-server@.service" SERVER_UNIT = DEPLOY / "files/usr/local/lib/systemd/system/left4me-server@.service"
GAME_SLICE = DEPLOY / "files/usr/local/lib/systemd/system/l4d2-game.slice" GAME_SLICE = DEPLOY / "files/usr/local/lib/systemd/system/l4d2-game.slice"
BUILD_SLICE = DEPLOY / "files/usr/local/lib/systemd/system/l4d2-build.slice" BUILD_SLICE = DEPLOY / "files/usr/local/lib/systemd/system/l4d2-build.slice"
SYSCTL_CONF = DEPLOY / "files/etc/sysctl.d/99-left4me.conf"
GLOBAL_REFRESH_SERVICE = DEPLOY / "files/usr/local/lib/systemd/system/left4me-refresh-global-overlays.service" GLOBAL_REFRESH_SERVICE = DEPLOY / "files/usr/local/lib/systemd/system/left4me-refresh-global-overlays.service"
GLOBAL_REFRESH_TIMER = DEPLOY / "files/usr/local/lib/systemd/system/left4me-refresh-global-overlays.timer" GLOBAL_REFRESH_TIMER = DEPLOY / "files/usr/local/lib/systemd/system/left4me-refresh-global-overlays.timer"
SANDBOX_UNIT_DIR = DEPLOY / "files/usr/local/lib/systemd/system" SANDBOX_UNIT_DIR = DEPLOY / "files/usr/local/lib/systemd/system"
@ -128,6 +129,21 @@ def test_l4d2_build_slice_exists_with_low_weights():
assert "IOWeight=10" in text assert "IOWeight=10" in text
def test_sysctl_conf_present_with_perf_settings():
assert SYSCTL_CONF.is_file()
text = SYSCTL_CONF.read_text()
for line in (
"net.core.rmem_max = 8388608",
"net.core.wmem_max = 8388608",
"net.core.rmem_default = 524288",
"net.core.wmem_default = 524288",
"net.core.netdev_max_backlog = 5000",
"net.core.netdev_budget = 600",
"vm.swappiness = 10",
):
assert line in text, f"missing {line!r} in 99-left4me.conf"
def _fake_command(tmp_path, command_name): def _fake_command(tmp_path, command_name):
marker = tmp_path / f"{command_name}.args" marker = tmp_path / f"{command_name}.args"
command = tmp_path / command_name command = tmp_path / command_name