Re: [PATCH v2] sched/fair: Prefer cache locality for EAS wakeup

[Christian Loehle <christian.loehle@arm.com>]

On 10/31/25 16:59, Shubhang Kaushik OS wrote:
> Yes, I agree that EAS approach is not suitable in this case as they require a heterogenous CPU topology.
> The issue is that the existing checks are for a completely idle CPU, whereas `cpu_overutilized` implies
> the CPU is busy but not yet overloaded. I ventured into EAS as this `cpu_overutilized` relies on
> `sched_energy_enabled()` being active. The point I wanted to convey is that - we still need a `cpu_busy?`
> check to make use of the cache locality - for SMP systems. Would appreciate some pointers on the same lines..

So the main issue is that with existing code if a CPU is "overloaded" isn't all that well defined.
For EAS we know if !rd->overloaded => all CPUs are !cpu_overutilized(). We could just pick any where
the task still fits (and we do).
For SMP what 'overloaded' will actually mean depends on the rest of the system (or at least domain). 


> Regards,
> Shubhang
> [sip]