Re: [PATCH v2 3/3] cgroup, docs: cpu controller interaction with various scheduling policies

[Shashank Balaji <shashank.mahadasyam@sony.com>]

Hi Tejun,

On Tue, May 20, 2025 at 10:16:38AM -1000, Tejun Heo wrote:
> Hello,
> 
> On Tue, May 20, 2025 at 11:07:47PM +0900, Shashank Balaji via B4 Relay wrote:
> ...
> > +The interaction of a process with the cpu controller depends on its scheduling
> > +policy. We have the following scheduling policies: ``SCHED_IDLE``, ``SCHED_BATCH``,
> > +``SCHED_OTHER``, ``SCHED_EXT`` (if ``CONFIG_SCHED_CLASS_EXT`` is enabled), ``SCHED_FIFO``,
> > +``SCHED_RR``, and ``SCHED_DEADLINE``. ``SCHED_{IDLE,BATCH,OTHER,EXT}`` can be scheduled
> > +either by the fair-class scheduler or by a BPF scheduler::
> > +
> > +    CONFIG_SCHED_CLASS_EXT
> > +    ├─ Disabled
> > +    |   └─ SCHED_{IDLE,BATCH,OTHER} -> fair-class scheduler
> > +    └─ Enabled
> > +        ├─ BPF scheduler disabled
> > +        |   └─ SCHED_{IDLE,BATCH,OTHER,EXT} -> fair-class scheduler
> > +        ├─ BPF scheduler without SCX_OPS_SWITCH_PARTIAL enabled
> > +        |   └─ SCHED_{IDLE,BATCH,OTHER,EXT} -> BPF scheduler
> > +        └─ BPF scheduler with SCX_OPS_SWITCH_PARTIAL enabled
> > +            ├─ SCHED_{IDLE,BATCH,OTHER} -> fair-class scheduler
> > +            └─ SCHED_EXT -> BPF scheduler
> > +
> > +For more details on ``SCHED_EXT``, check out :ref:`Documentation/scheduler/sched-ext.rst. <sched-ext>`
> > +From the point of view of the cpu controller, processes can be categorized as
> > +follows:
> > +
> > +* Processes under the fair-class scheduler
> > +* Processes under a BPF scheduler with the ``cgroup_set_weight`` callback
> > +* Everything else: ``SCHED_{FIFO,RR,DEADLINE}`` and processes under a BPF scheduler
> > +  without the ``cgroup_set_weight`` callback
> > +
> > +Note that the ``cgroup_*`` family of callbacks require ``CONFIG_EXT_GROUP_SCHED``
> > +to be enabled. For each of the following interface files, the above categories
> > +will be referred to. All time durations are in microseconds.
> 
> Can we document the above in sched_ext documentation and point to it from
> here? Documenting sched_ext details here seems a bit out of place and prone
> to becoming stale over time.

Got it. Apart from that, is the content alright? 

> Can you please separate out indentation changes to a separate patch? These
> usually make reviewing tricky.

Got it.

Thank you

Regards,
Shashank

PS: Apologies for any malformed emails. I finally managed to switch from Outlook
to mutt.