RE: O(1) scheduler seems to lock up on sched_FIFO and sched_RR ta sks

Perez-Gonzalez, Inaky
2003-06-19T04:24:17Z

> From: 'joe.korty@ccur.com' [mailto:joe.korty@ccur.com]
>
> On Wed, Jun 18, 2003 at 06:44:42PM -0700, Perez-Gonzalez, Inaky wrote:
> >
> > Now that we are at that, it might be wise to add a higher-than-anything
> > priority that the kernel code can use (what would be 100 for user space,
> > but off-limits), so even FIFO 99 code in user space cannot block out
> > the migration thread, keventd and friends.
>
> I would prefer users have the ability to put one or two truly critical RT
> tasks above keventd & family. Such tasks would have to follow certain
rules
> .. run & sleep quick .. limited or no device IO .. most communication to
> other tasks through shared memory .. possibly others.

Agreed - see my answers to George Anzinger and Robert Love; I wasn't
precise enough on meaning "yeah, you should be able to reprioritize it
at will". My point is that user programs have a limit that they cannot
use, while kernel threads can use the user's priority space and their
highest priority space.

Iñaky Pérez-González -- Not speaking for Intel -- all opinions are my own
(and my fault)