Re: [PATCH v3 15/20] sched/core: Introduce a simple steal monitor

[Ilya Leoshkevich]

On 5/14/26 17:21, Shrikanth Hegde wrote:
> Start with a simple steal monitor.
>
> It is meant to look at steal time and make the decision to
> reduce/increase the preferred CPUs.
>
> It has
> - work function to execute the steal time calculations and decision
>    making periodically.
> - temporary cpumask, which will be used in the work function. This helps
>    to avoid cpumask allocation in periodic work function.
> - low and high thresholds for steal time.
> - sampling period to control the frequency of steal time calculations.
> - cache the previous decision to avoid oscillations
>
> Signed-off-by: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx>
> ---
>   include/linux/sched.h | 13 +++++++++++++
>   kernel/sched/core.c   | 24 ++++++++++++++++++++++++
>   kernel/sched/sched.h  |  3 +++
>   3 files changed, 40 insertions(+)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index dcfb57c90850..ee5f19a96118 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h

[...]

> @@ -11351,4 +11353,26 @@ void sched_push_current_non_preferred_cpu(struct rq *rq)
>   			    push_task, this_cpu_ptr(&npc_push_task_work));
>   	local_irq_restore(flags);
>   }
> +
> +struct steal_monitor_t steal_mon;
> +
> +void sched_init_steal_monitor(void)
> +{
> +	INIT_WORK(&steal_mon.work, sched_steal_detection_work);
> +	zalloc_cpumask_var(&steal_mon.tmp_mask, GFP_KERNEL);

Error handling is missing.

[...]