Re: [PATCH sched_ext/for-7.1] sched_ext: idle: Prioritize idle SMT sibling

[Daniel Jordan]

Hi Andrea,

On Wed, Mar 18, 2026 at 01:38:42AM +0100, Andrea Righi wrote:
> In the default built-in idle CPU selection policy, when @prev_cpu is
> busy and no fully idle core is available, try to place the task on its
> SMT sibling if that sibling is idle, before searching any other idle CPU
> in the same LLC.
> 
> Migration to the sibling is cheap and keeps the task on the same core,
> preserving L1 cache and reducing wakeup latency.

Seems reasonable.

> On large SMT systems this appears to consistently boost throughput by
> roughly 2-3% on CPU-bound workloads (running a number of tasks equal to
> the number of SMT cores).

What workloads out of curiosity?