Re: [RFC][PATCH 1/2] sched: Extended scheduler time slice

On Thu, Feb 06, 2025 at 02:53:53PM +0100, Sebastian Andrzej Siewior wrote:

On 2025-02-06 14:48:59 [+0100], Peter Zijlstra wrote:

quoted

On Thu, Feb 06, 2025 at 02:44:08PM +0100, Sebastian Andrzej Siewior wrote:

quoted

SCHED_OTHER vs SCHED_OTHER after all. But please don't delay a wakeup of
SCHED_FIFO/ RR/ DL because of this LAZY hint.

Thing will get delayed if interrupts are disabled or kernel has
preemption disabled too. So as long as we ensure hint crap is of equal
order, nothing cares if you do.

If you can't tell the difference between task does hint crap in
userspace and task is in the middle of syscall, you can't tell the
difference.

I can tell the difference if I see a trace where an interrupt fires,
performs a wakeup and the SCHED_OTHER task remains on CPU while the task
SCHED_FIFO task sits on the runqueue until a timer fires.

Right, but so what? Same delay will happen if interrupt fires in the
middle of a preempt_disable() region.

Or if interrupt gets pending while interrupts are disabled, except your
trace will not show that.

Your worst case response time isn't affected. That's all that matters.