[Wings] Support CPU burst on top of the CFS quota — bursty game servers get hard-throttled on spikes

[menukaabhimandev]

Component: Wings.

Wings applies cpu_limit as a plain CFS quota (quota = limit × 1000 over a 100ms period). That's a hard ceiling on every 100ms window, which is rough for game servers since their CPU usage is bursty, not steady.

example: a Minecraft server sitting at 8% CPU overall. A player teleports somewhere new, the map loads, and for 2-3 seconds the server legitimately wants 150% of a core. With a plain quota it gets throttled mid-spike, players lag, and then it's back to 8% for the next hour. The average usage never got close to the limit, but the ceiling still bit.

The only workaround right now is raising cpu_limit — which then lets the server actually burn that much constantly. You can't give headroom for spikes without giving it away all the time, and on shared nodes that's a tradeoff admins have to make every day.

cgroup v2 already has the mechanism for this: cpu.max-burst (kernel 5.14+). It lets a task bank unused runtime and spend it on short spikes, so a 100% quota with a burst budget allows the spike without changing the steady-state limit. On cgroup v1 there's no equivalent, so the setting would just be ignored there.

Roughly how I'd see it:

• Panel: add a cpu_burst limit next to cpu_limit in the build settings, default 0/disabled so existing installs see no change.
• Wings: when creating the container, if cpu_burst > 0 and the cgroup is v2, write cpu.max-burst alongside the existing quota.

For context, we've been running exactly this on our own nodes (a patched wings writing the burst value) and the teleport/map-load stutter went away without changing anyone's steady-state limit. Happy to share the implementation details if that helps.