Re: yield API

[Douglas McNaught]

"linux-os \(Dick Johnson\)" <linux-os@xxxxxxxxxxxx> writes:

> Whether or not there is a POSIX definition of sched_yield(),
> there is a need for something that will give up the CPU
> and not busy-wait. There are many control applications
> where state-machines are kept in user-mode code. The code
> waits for an event. It shouldn't be spinning, wasting
> CPU time, when the kernel can be doing file and network
> I/O with the wasted CPU cycles.

These "control applications" would be real-time processes, for which
(AIUI) sched_yield() behavior is completely well-defined and
implemented as such by Linux.  The question here is how useful the
call is for SCHED_OTHER (non-real-time) processes, for which it has no
well-defined semantics.

-Doug
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