Re: [PATCH v4 4/4] sched/fair: Check the SD_ASYM_PACKING flag in sched_use_asym_prio()

Ricardo Neri
2024-02-10T01:11:07Z

On Wed, Feb 07, 2024 at 11:47:04AM +0800, alexs@kernel.org wrote:
> From: Alex Shi <alexs@kernel.org>
>
> sched_use_asym_prio() checks whether CPU priorities should be used. It
> makes sense to check for the SD_ASYM_PACKING() inside the function.
> Since both sched_asym() and sched_group_asym() use sched_use_asym_prio(),
> remove the now superfluous checks for the flag in various places.

Reviewed-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>

Tested on Alder Lake and Meteor Lake, which use asym_packing.

Tested-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>

>
> Signed-off-by: Alex Shi <alexs@kernel.org>
> To: linux-kernel@vger.kernel.org
> To: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
> To: Ben Segall <bsegall@google.com>
> To: Steven Rostedt <rostedt@goodmis.org>
> To: Dietmar Eggemann <dietmar.eggemann@arm.com>
> To: Valentin Schneider <vschneid@redhat.com>
> To: Daniel Bristot de Oliveira <bristot@redhat.com>
> To: Vincent Guittot <vincent.guittot@linaro.org>
> To: Juri Lelli <juri.lelli@redhat.com>
> To: Peter Zijlstra <peterz@infradead.org>
> To: Ingo Molnar <mingo@redhat.com>
> ---
> kernel/sched/fair.c | 16 +++++++---------
> 1 file changed, 7 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 942b6358f683..10ae28e1c088 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -9740,6 +9740,9 @@ group_type group_classify(unsigned int imbalance_pct,
> */
> static bool sched_use_asym_prio(struct sched_domain *sd, int cpu)
> {
> + if (!(sd->flags & SD_ASYM_PACKING))
> + return false;
> +
> if (!sched_smt_active())
> return true;
>
> @@ -9941,11 +9944,9 @@ static inline void update_sg_lb_stats(struct lb_env *env,
> sgs->group_weight = group->group_weight;
>
> /* Check if dst CPU is idle and preferred to this group */
> - if (!local_group && env->sd->flags & SD_ASYM_PACKING &&
> - env->idle != CPU_NOT_IDLE && sgs->sum_h_nr_running &&
> - sched_group_asym(env, sgs, group)) {
> + if (!local_group && env->idle != CPU_NOT_IDLE && sgs->sum_h_nr_running &&
> + sched_group_asym(env, sgs, group))
> sgs->group_asym_packing = 1;
> - }
>
> /* Check for loaded SMT group to be balanced to dst CPU */
> if (!local_group && smt_balance(env, sgs, group))
> @@ -11041,9 +11042,7 @@ static struct rq *find_busiest_queue(struct lb_env *env,
> * If balancing between cores, let lower priority CPUs help
> * SMT cores with more than one busy sibling.
> */
> - if ((env->sd->flags & SD_ASYM_PACKING) &&
> - sched_asym(env->sd, i, env->dst_cpu) &&
> - nr_running == 1)
> + if (sched_asym(env->sd, i, env->dst_cpu) && nr_running == 1)
> continue;
>
> switch (env->migration_type) {
> @@ -11139,8 +11138,7 @@ asym_active_balance(struct lb_env *env)
> * the lower priority @env::dst_cpu help it. Do not follow
> * CPU priority.
> */
> - return env->idle != CPU_NOT_IDLE && (env->sd->flags & SD_ASYM_PACKING) &&
> - sched_use_asym_prio(env->sd, env->dst_cpu) &&
> + return env->idle != CPU_NOT_IDLE && sched_use_asym_prio(env->sd, env->dst_cpu) &&
> (sched_asym_prefer(env->dst_cpu, env->src_cpu) ||
> !sched_use_asym_prio(env->sd, env->src_cpu));
> }
> --
> 2.43.0
>