Linux Device Drivers Development

Softirqs and ksoftirqd

A 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 directly. There are only networks and block device subsystems using softirq. Tasklets are an instantiation of softirqs, and will be sufficient in almost every case when you feel the need to use softirqs.