本文介绍了Linux内核中用于延后工作的三种主要机制：软中断（softirqs）、任务集（tasklets）和工作队列（workqueues）。软中断作为底层机制主要用于网络、SCSI及定时器等性能敏感子系统；任务集则更易于使用，适用于大多数场景除非对扩展性和速度有特别需求；工作队列允许睡眠并可调用阻塞函数如互斥锁。
The following mechanisms are available in the kernel to defer work to a bottom half: softirqs, tasklets, and work queues .
Softirqs
are the basic bottom half mechanism and have strong locking requirements. They are used only by a
few performance-sensitive
subsystems such as the networking layer, SCSI layer, and kernel timers.
Tasklets
are built on top of softirqs and are easier to use. It's recommended
to use tasklets unless you have crucial
scalability or speed requirements.
A primary difference between a softirq and a tasklet is that the former is reentrant whereas the latter isn't. Different instances of a softirq can run simultaneously on different processors, but that is not the case with tasklets.
Work queues
are a third way to defer work from interrupt handlers. They execute in process context
and are
allowed to sleep
, so they can use drowsy functions such as mutexes.
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