In Linux, the handling of interrupt handler is divided into two components : top half, and bottom half.
From my understanding, the bottom-half of an interrupt handler can be handled in many ways : softirq, tasklet, work-queue, and timer-list.
I want to know which function(s) in the Linux kernel handle the schedule function of these bottom-halves.
Edit : I looked into the halndling of softirq's and tasklet's, and it seems that both of them are handled through the __do_softirq (http://lxr.linux.no/linux+v2.6.32.58/kernel/softirq.c#L207) function. However, I still see many paths inside the handler execution which pass through the schedule() function of the Linux kernel, and then show divergence. I am not able to explain these paths properly.
Some intuition for guiding you towards this function :
The scheduling of pending task (bottom-half) should be triggered by some event. Kernel events can either be a system call, or an interrupt.I think that the event which triggers a bottom half is an interrupt and not a system call.
As per my knowledge, this are the steps followed on arrival of an interrupt :
1. Interrupt arrives at core
2. Top half of the interrupt handler is run
3. Check the pending queue to see if there is a task which needs attention.
4. If there is any pending task, then execute it
I was going through the function list of all the OS handlers, and observed that the execution of many handlers passed through the schedule() function of the Linux kernel. Since this function is called so often from many interrupt handlers, I suppose that the bottom half of the interrupt handlers should be called from within this function only.
The schedule() function calls the post_schedule() function at the end. I tracked all the functions between this two function calls. There are many different function lists between them, raising suspicion that the bottom half functions must lie on the path from schedule() to post_schedule(). However, the sheer number of different MACROS and functions in the kernel is making it really difficult to pinpoint the function from where the scheduler jumps into the bottom half.
