Re: [PATCH] Time sliced CFQ #2

[Robert Love <rml@novell.com>]

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