Re: [PATCH v3 4/4] sched/fair: Check the SD_ASYM_PACKING flag in sched_use_asym_prio()

kuiliang Shi
2024-02-06T07:57:35Z

On 2/6/24 6:38 AM, Ricardo Neri wrote:
> On Thu, Feb 01, 2024 at 07:54:47PM +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"
>
> s/places"/places./
>
>>
>> Signed-off-by: Alex Shi <alexs@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 | 15 +++++++--------
>> 1 file changed, 7 insertions(+), 8 deletions(-)
>>
>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>> index 44fd5e2ca642..bd32efbea688 100644
>> --- a/kernel/sched/fair.c
>> +++ b/kernel/sched/fair.c
>> @@ -9741,6 +9741,9 @@ 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;
>>
>> @@ -9940,11 +9943,9 @@ 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))
>
> You should align sched_group_asym() to !local_group.

Thanks for all suggestion. I will take them in next version.

>
>> sgs->group_asym_packing = 1;
>> - }
>>
>> /* Check for loaded SMT group to be balanced to dst CPU */
>> if (!local_group && smt_balance(env, sgs, group))
>> @@ -11040,9 +11041,7 @@ 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) {
>> @@ -11138,7 +11137,7 @@ 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) &&
>> + return env->idle != CPU_NOT_IDLE &&
>> sched_use_asym_prio(env->sd, env->dst_cpu) &&
>> (sched_asym_prefer(env->dst_cpu, env->src_cpu) ||
>
> Perhaps you can rearrange the spaghetti of conditions to make better use of
> the full 80-column line.

80-column doesn't work here, will try 100 column.

Thanks
Alex