Re: [PATCH v4 3/5] sched/fair: Switch to task based throttle model

[Aaron Lu <ziqianlu@bytedance.com>]

On Thu, Sep 04, 2025 at 08:04:01PM +0800, Aaron Lu wrote:
... ...
> Per my understanding, we keep PELT clock running because we want the
> throttled cfs_rq's load to continue get update when it still has tasks
> running in kernel mode and have that up2date load could let it have a
> hopefully more accurate weight through update_cfs_group(). So it looks
> to me, if PELT clock should not be stopped, then we should not abort in
> propagate_entity_cfs_rq() and update_cfs_group(). I missed these two
> aborts in these two functions, but now you and Peter have pointed this
> out, I suppose there is no doubt we should not abort in
> update_cfs_group() and propagate_entity_cfs_rq()? If we should not mess
> with shares distribution, then the up2date load is not useful and why
> not simply freeze PELT clock on throttle :)

With more thinking, when PELT clock is running, root level cfs_rq's load
can be updated and that is useful for things like load balance.

update_cfs_group() is a different story and as Ben said, there is cons
and pros whether to abort there for throttled cfs_rq so there's no
obvious thing to do for it.