sched_wakeup_granularity_ns in CFS correctly designed or not?

[Rohith R]

> OK, let me get this straight:
> 1) Your application has a deadline.
> 2) You do not tell the kernel of that deadline.
> 3) You want to know if the kernel will keep the
>    promise you never told it about?
>

Yes. All I am saying is that by keeping a
*sched_wakeup_granularity_ns *parameter
as 2.5 ms. A process which is waken up has to wait for that much amount of
time if any other (non-important) process is executing. Now I am saying
that the way CFS seems to be designed it will never make a process which
wakes up and has a deadline < 2.5 ms meet its deadline.

Now why does this scenario matter. This may occur in real workloads like
video processing etc.

I do not want any guarantee that CFS will meet deadline that I did not even
give it (or its not even aware of). But one sure would like a guarantee
that CFS surely will not fail all the time in such scenarios (which is my
claim).

Is that really your question?

I hope the question makes sense now.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20170611/ff831c3f/attachment.html