Work deferring mechanism

Deferring is a method by which you schedule a piece of work to be executed in the future. It's a way to report an action later. Obviously, the kernel provides facilities to implement such a mechanism; it allows you to defer functions, whatever their type, to be called and executed later. There are three of them in the kernel:

• SoftIRQs: Executed in an atomic context
• Tasklets: Executed in an atomic context
• Workqueues: Executed in a process context

Softirqs and ksoftirqd

Software IRQ (softirq), or software interrupt is a deferring mechanism used only for very fast processing, since it runs with a disabled scheduler (in an interrupt context). You'll rarely (almost never) want to deal with softirq...