Re: [PATCH v6 14/16] sched_ext: Export task_is_scx_enabled() for verification

[Gabriele Monaco]

Hello,

On Thu, 2026-02-26 at 05:22 -1000, Tejun Heo wrote:
> Hello,
> 
> On Thu, Feb 26, 2026 at 08:10:52AM +0100, Gabriele Monaco wrote:
> > On Wed, 2026-02-25 at 07:08 -1000, Tejun Heo wrote:
> > > On Wed, Feb 25, 2026 at 10:51:20AM +0100, Gabriele Monaco wrote:
> > > > Export a task_is_scx_enabled() to allow quick classification by using
> > > > the scx state SCX_TASK_ENABLED.
> > > 
> > > This test already exists - task_on_scx(). Please feel free to move that
> > > out to include/linux/sched/ext.h.
> > 
> > I see task_on_scx() is used in what looks like some sched core hot paths (
> > pick_next_task() -> prio_less()), but I presume not inlining it isn't a big
> > issue.
> 
> I mean, you can always export what task_on_scx() accesses.

I'm not sure what the cleanest thing is here

task_on_scx() is
  scx_enabled() && p->sched_class == &ext_sched_class

scx_enabled() might as well be exported (together with its static key), but I'm
not sure exporting the sched_class is the right thing, since all those scheduler
things are quite private.

On the other hand, task_is_scx_enabled() (added in this patch) is
  scx_get_task_state(p) == SCX_TASK_ENABLED

and scx_get_task_state() is
  (p->scx.flags & SCX_TASK_STATE_MASK) >> SCX_TASK_STATE_SHIFT

those are pretty much already exported.

If those are really equivalent, wouldn't it be simpler to export
scx_get_task_state() and use that in an exported (still inlined) version of
task_on_scx() ?

If you think exporting a sched_class is just fine I'd follow on with your
suggestion without bothering, though.

Thanks,
Gabriele