Re: [PATCH 0/3] sched/tick: Decouple sched_tick() from HZ

[Qais Yousef]

On 05/17/26 05:07, Qais Yousef wrote:
> Previous attempt to make HZ 1000 the default [1] to help with scheduler
> responsiveness didn't get merged. But maybe for the best, as I think this idea
> of decoupling sched_tick() from HZ makes more sense. We shouldn't need to make
> a choice between how often timers should trigger vs how often should the
> scheduler update its stats/take decisions.
> 
> With HRTICK now is default on, preemption checks are less of problem. But tasks
> could need to migrate (specifically on HMP systems) and frequencies could need
> updating for solo long running tasks.
> 
> The conversion is half complete. We need to invent a new jiffy (piffy?) and
> move existing load balancing logic (and potentially other users if they want
> to) to speed them up. BUT, with push load balancer patches circulating around,
> I am not sure it is worth while or desired to speed it since we have a better
> faster mechanism to keep the system balanced without the need for the 'heavy
> handed' full load balance to trigger. The push lb can benefit from this ptick
> too to ensure more responsiveness.

Err, this whole series is RFC. Forgot to add the tag, sorry.

> 
> [1] https://lore.kernel.org/lkml/20250226000810.459547-1-qyousef@xxxxxxxxxxx/
> 
> Qais Yousef (3):
>   sched/tick: Decouple sched_tick() from HZ
>   sched/tick: Move TICK_NSEC users to PTICK_NSEC
>   sched/tick: Turn on PTICK by default
> 
>  kernel/sched/clock.c             |  4 +-
>  kernel/sched/core.c              | 78 +++++++++++++++++++++++++++++---
>  kernel/sched/cpufreq_schedutil.c |  2 +-
>  kernel/sched/fair.c              |  6 +--
>  kernel/sched/features.h          |  8 ++++
>  kernel/sched/sched.h             |  7 +++
>  6 files changed, 93 insertions(+), 12 deletions(-)
> 
> -- 
> 2.34.1
>