Re: [PATCH v4 1/6] sched/fair: Do not skip CPUs of similar capacity with busy SMT siblings

[Christian Loehle]

On 6/8/26 13:57, Ricardo Neri wrote:
> When picking a busiest CPU with only one running task, the function
> sched_balance_find_src_rq() skips candidate CPUs if the destination CPU has
> less than ~5% extra capacity. This condition only holds if all the SMT
> siblings of a CPU are idle.
> 
> SMT siblings share the computing resources of a physical core and this
> results in reduced capacity if more than one sibling is busy.
> 
> Skipping a CPU as described would prevent the load balancer from pulling
> tasks from a scheduling group previously and correctly identified as
> group_smt_balance (i.e., one with more than one task running).
> 
> Do not skip a candidate CPU of similar capacity if it has busy SMT
> siblings.
> 
> Signed-off-by: Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx>

Nice find!
Reviewed-by: Christian Loehle <christian.loehle@xxxxxxx>

> [snip]