Re: sched/deadline: Use revised wakeup rule for dl_server

[Andreas Ziegler]

Hi Juri, Everyone

On 2026-05-11 12:46, Juri Lelli wrote:
> Hello,
>
> On 08/05/26 08:09, Andreas Ziegler wrote:
> > Linux kernel version: 6.12
> >   CONFIG_PREEMPT_RT (w/ PREEMPT_RT patch applied)
> > Architecture: aarch64
> > Platform: Raspberry Pi 4
> >
> > Hi everyone,
> >
> > Commit d66792919d4f (sched/deadline: Use revised wakeup rule for 
> > dl_server)
> > [1] introduced a marked degradation in scheduling latency for 
> > real-time
> > tasks in the presence of heavy I/O load.
>
> Can this be the same regression reported here?
>
> https://marc.info/?l=linux-rt-users&m=177844667227991
>
> Please notice the list of missing subsequent fixes Mike is suggesting 
> to
> test with.
>
> https://marc.info/?l=linux-rt-users&m=177847863710263&w=2

The patch set works for me so far.

  cccb45d7c429 ("sched/deadline: Less agressive dl_server handling") 
(6.17)
  4ae8d9aa9f9d ("sched/deadline: Fix dl_server getting stuck") (6.17)
  a3a70caf7906 ("sched/deadline: Fix dl_server behaviour") (6.17)

> Thanks,
> Juri

Kind regards,
Andreas