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