On Mon, 30 Nov 2020 at 15:40, Mel Gorman <[email protected]> wrote: > > The clearing of SMT siblings from the SIS mask before checking for an idle > core is a small but unnecessary cost. Defer the clearing of the siblings > until the scan moves to the next potential target. The cost of this was > not measured as it is borderline noise but it should be self-evident.
Good point > > Signed-off-by: Mel Gorman <[email protected]> Reviewed-by: Vincent Guittot <[email protected]> > --- > kernel/sched/fair.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 0d54d69ba1a5..d9acd55d309b 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6087,10 +6087,11 @@ static int select_idle_core(struct task_struct *p, > struct sched_domain *sd, int > break; > } > } > - cpumask_andnot(cpus, cpus, cpu_smt_mask(core)); > > if (idle) > return core; > + > + cpumask_andnot(cpus, cpus, cpu_smt_mask(core)); > } > > /*
