October 2017
Intermediate to advanced
586 pages
14h 8m
English
Content preview from Linux Device Drivers Development
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Softirqs as bottom half
As said at the beginning of this chapter, we will not discuss softirq. Tasklets will be enough wherever you feel the need to use softirqs. Anyway, let's talk about their defaults.
Softirqs run in a software interrupt context, with preemption disabled, holding the CPU until they complete. Softirqs should be fast; otherwise they may slow the system down. When, for any reason, a softirq prevents the kernel from scheduling other tasks, any new incoming softirq will be handled by ksoftirqd threads, running in a process context.