FreeBSD Device Drivers

Taskqueues

Taskqueues allow drivers to schedule the asynchronous execution of one or more functions at a later time. These functions are known as tasks. Taskqueues are primarily used for deferred work.

Note

Taskqueues are like callouts except that you can’t specify the time to execute your functions.

Taskqueues work by having tasks queued on them. Intermittently, these tasks get executed.

Global Taskqueues

FreeBSD runs and maintains four global taskqueues:

taskqueue_swi

The taskqueue_swi taskqueue executes its tasks in the context of an interrupt. Interrupt handlers typically defer their computationally expensive work to this taskqueue. This taskqueue lets interrupt handlers finish sooner, thereby reducing the amount of time spent with interrupts disabled. ...