[coyotos-dev] Sleep for interval

[William Leslie]

On 10/5/07, Jonathan S. Shapiro <shap at eros-os.com> wrote:
>
> Suppose, for a moment, that *all* sleep handling is done at user level.
> We then require a user-level sleep agent that can wait for the interval
> clock interrupt.  Unfortunately, the kernel must *also* wait for the
> interval clock interrupt in order to implement preemption and primary
> scheduling functions.
>
> Having two parties attempt to handle an interrupt independent of each
> other is just begging for problems.


You could have the kernel hand off control to the scheduler after the
interrupt, and if a task was supposed to be given control at this critical
time, it will be next on the list. It seems like the important thing with
preemption here is that a task is forward enough in the list to receive
control in a timely manner, which is part of the process of ordering the
list.
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