Re: [PATCH] Time sliced CFQ #2

[Kyle Moffett]

On Dec 05, 2004, at 21:34, Con Kolivas wrote:
> I think when nice is changed, ioprio needs to be changed with it as a 
> sane
> default action. I suspect that most of the time people will not use the
> separate ioprio call, but using 'nice' is a regular linuxy thing to 
> do. Ideally
> we make ioprio part of the 'nice' utility and we specify both at the 
> same time.
> Something like: "nice -n 5 -i 20 blah"

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:

nice = x;		/* -20 to 20 */
ioprio = y;		/* -20 to 20 */
effective_ioprio = ((ioprio<0)?(20+nice):(20-nice))  *  abs(ioprio)/20;
			/* -20 to 20 */

Cheers,
Kyle Moffett

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