Tickless/event-driven kernel

[Martin Decky]

The kernels of many operating systems have already switched or are planning to switch to tickless operation (i.e. avoiding strictly periodic timer interrupts and scheduling timers on-demand).

The benefits are lower overhead, better power-saving possibilities (even without any specific power management features) and a more natural design of the timers without a fixed timer period. The most significant drawback is naturally more complex timer bookkeeping, but as empirical evidence shows it is manageable.

Clarification: The term "tickless" is usually understood as a means to avoid periodic timer interrupts in idle states. However, an "event-driven" kernel design can actually go even further and avoid all periodic timer interrupts. See the following references in the context of Linux:

• ​http://linuxplumbersconf.org/ocw/proposals/103
• ​http://events.linuxfoundation.org/sites/events/files/eeus13_mckenney.pdf