[PATCH] sched_ext: Documentation: Mention scheduling class precedence

[PATCH] sched_ext: Documentation: Mention scheduling class precedence

[Christian Loehle]

Mention the scheduling class precedence of fair and sched_ext to
clear up how sched_ext partial mode works.

Signed-off-by: Christian Loehle <christian.loehle@arm.com>
---
 Documentation/scheduler/sched-ext.rst | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/scheduler/sched-ext.rst b/Documentation/scheduler/sched-ext.rst
index 9e2882d937b4..100d45963781 100644
--- a/Documentation/scheduler/sched-ext.rst
+++ b/Documentation/scheduler/sched-ext.rst
@@ -58,7 +58,8 @@ in ``ops->flags``, all ``SCHED_NORMAL``, ``SCHED_BATCH``, ``SCHED_IDLE``, and
 However, when the BPF scheduler is loaded and ``SCX_OPS_SWITCH_PARTIAL`` is
 set in ``ops->flags``, only tasks with the ``SCHED_EXT`` policy are scheduled
 by sched_ext, while tasks with ``SCHED_NORMAL``, ``SCHED_BATCH`` and
-``SCHED_IDLE`` policies are scheduled by the fair-class scheduler.
+``SCHED_IDLE`` policies are scheduled by the fair-class scheduler which has
+higher sched_class precedence than ``SCHED_EXT``.
 
 Terminating the sched_ext scheduler program, triggering `SysRq-S`, or
 detection of any internal error including stalled runnable tasks aborts the
-- 
2.34.1

Re: [PATCH] sched_ext: Documentation: Mention scheduling class precedence

[Andrea Righi]

On Fri, Mar 06, 2026 at 10:30:51AM +0000, Christian Loehle wrote:
> Mention the scheduling class precedence of fair and sched_ext to
> clear up how sched_ext partial mode works.
> 
> Signed-off-by: Christian Loehle <christian.loehle@arm.com>

Agreed, clarifying fair scheduling precedence here can help better
understand the implications of partial mode.

Acked-by: Andrea Righi <arighi@nvidia.com>

Thanks,
-Andrea

> ---
>  Documentation/scheduler/sched-ext.rst | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/scheduler/sched-ext.rst b/Documentation/scheduler/sched-ext.rst
> index 9e2882d937b4..100d45963781 100644
> --- a/Documentation/scheduler/sched-ext.rst
> +++ b/Documentation/scheduler/sched-ext.rst
> @@ -58,7 +58,8 @@ in ``ops->flags``, all ``SCHED_NORMAL``, ``SCHED_BATCH``, ``SCHED_IDLE``, and
>  However, when the BPF scheduler is loaded and ``SCX_OPS_SWITCH_PARTIAL`` is
>  set in ``ops->flags``, only tasks with the ``SCHED_EXT`` policy are scheduled
>  by sched_ext, while tasks with ``SCHED_NORMAL``, ``SCHED_BATCH`` and
> -``SCHED_IDLE`` policies are scheduled by the fair-class scheduler.
> +``SCHED_IDLE`` policies are scheduled by the fair-class scheduler which has
> +higher sched_class precedence than ``SCHED_EXT``.
>  
>  Terminating the sched_ext scheduler program, triggering `SysRq-S`, or
>  detection of any internal error including stalled runnable tasks aborts the
> -- 
> 2.34.1
> 

Re: [PATCH] sched_ext: Documentation: Mention scheduling class precedence

[Tejun Heo]

Applied to sched_ext/for-7.0-fixes.

Thanks.

--
tejun