Table of Contents
What are the different bottom half mechanisms in Linux?
Work queues are a very simple yet useful method of queueing work to later be performed in process context. We will get to them later. Consequently, today 2.6 has three bottom-half mechanisms in the kernel: softirqs, tasklets, and work queues.
How are interrupts implemented in Linux?
In Linux the interrupt handling is done in three phases: critical, immediate and deferred. In the first phase the kernel will run the generic interrupt handler that determines the interrupt number, the interrupt handler for this particular interrupt and the interrupt controller.
What is bottom half and top half in Linux?
The so-called top half is the routine that actually responds to the interrupt—the one you register with request_irq. The bottom half is a routine that is scheduled by the top half to be executed later, at a safer time.
What is Softirq and Tasklets?
Generally speaking, softirqs are re-entrant functions and must explicitly protect their data structures with spin locks. Tasklets differ from softirqs because a tasklet is always serialized with respect to itself; in other words, a tasklet cannot be executed by two CPUs at the same time.
What is the difference between Workqueue and Tasklet?
A tasklet always runs in the interrupt context, that means when a tasklet executes it is as if the processor is executing an interrupt service routine. On the other hand a workqueue executes as a normal process and not a interrupt, hence a worqueue can go to sleep it can hold semaphores.
How do you implement an interrupt?
Whenever an interrupt occurs, the controller completes the execution of the current instruction and starts the execution of an Interrupt Service Routine (ISR) or Interrupt Handler….Interrupt Priority in 8051.
| – | IP.7 | Not Implemented. |
|---|---|---|
| – | IP.4 | Not Implemented. |
| PT1 | IP.3 | Defines the Timer 1 interrupt priority level. |
What is a bottom half?
The bottom half of society comprises predominantly households that either have no working members, or are in the most marginal sectors of the working class (especially domestic and agricultural employment).
What are Tasklets in Linux?
Tasklet in Linux Kernel Tasklets are used to queue up work to be done at a later time. Tasklets can be run in parallel, but the same tasklet cannot be run on multiple CPUs at the same time. Also, each tasklet will run only on the CPU that schedules it, to optimize cache usage.
What is Tasklets Softirq and Workqueus and difference among them?
It is similar to tasklets with some differences. Workqueue functions run in the context of a kernel process, but tasklet functions run in the software interrupt context. This means that workqueue functions must not be atomic as tasklet functions.