Re: [PATCH v9] sched/fair: Filter false overloaded_group case for EAS

[Qais Yousef]

On 02/06/26 10:54, Vincent Guittot wrote:
> With EAS, a group should be set overloaded if at least 1 CPU in the group
> is overutilized but it can happen that a CPU is fully utilized by tasks
> because of clamping the compute capacity of the CPU. In such case, the CPU
> is not overutilized and as a result should not be set overloaded as well.
> 
> group_overloaded being a higher priority than group_misfit, such group can
> be selected as the busiest group instead of a group with a mistfit task
> and prevents load_balance to select the CPU with the misfit task to pull
> the latter on a fitting CPU.
> 
> Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
> Tested-by: Pierre Gondois <pierre.gondois@xxxxxxx>
> ---
> 
> This patch was part of a larger patchset [1] but makes sense on its own and has
> not changed since v2
> 
> [1] https://lore.kernel.org/all/20251202181242.1536213-1-vincent.guittot@xxxxxxxxxx/

I don't mind this. But I think with the original series misfit will be handled
better with push lb, and if it is made to handle overloaded case (which my
initial testing shows it is easily doable and I can't see clear bad impact
yet), I think we can retire overutilized altogether.

The current lb is slow, and doesn't do the right decision. Short circuiting to
wake up path via push is not only faster, but will also keep the decision tree
coherent whether it is EAS or something else.

Regardless of overloaded being handled in push lb or not, shouldn't your series
make misfit handling in pull lb obsolete anyway rendering this fix unnecessary?

It might be a good candidate for LTS though if there are reports.