Re: [PATCH] Time sliced CFQ #2

Robert Love
2004-12-06T05:12:59Z

On Mon, 2004-12-06 at 00:00 -0500, Kyle Moffett wrote:

> What about this:
>
> nice = x; /* -20 to 20 */
> ioprio = y; /* -40 to 40 */
> effective_ioprio = clamp(x+y); /* -20 to 20 */
>
> This would allow tuning processes for unusual contrasts with the ioprio
> call.
> On the other hand, it would allow us to just brute force "adjust" a
> process with
> the nice command in the usual way without any changes to the "nice"
> source.
>
> I also thought of a different effective ioprio calculation that scales
> instead of clamping:

I think the complication of all of this demonstrates the overcomplexity.
I think we need to either

(1) separate the two values. we have a scheduling
priority (distributing the finite resource of
processor time) and an I/O priority (distributing
the finite resource of disk bandwidth).
(2) just have a single value.

Personally, I prefer (1). But (2) is fine.

What we want to do either way is cleanly separate the concepts in the
kernel. That way we can decide what we actually expose to user-space.

Robert Love