[v5,3/5] sched/fair: Rework sched_use_asym_prio() and sched_asym_prefer()
Commit Message
From: Alex Shi <alexs@kernel.org>
sched_use_asym_prio() and sched_asym_prefer() are used together in various
places. Consolidate them into a single function sched_asym().
The existing sched_group_asym() is only used when collecting statistics
of a scheduling group. Rename it as sched_group_asym(), and remove the
obsolete function description.
This makes the code easier to read. No functional changes.
Tested-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Cc: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Reviewed-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
---
kernel/sched/fair.c | 45 ++++++++++++++++++++-------------------------
1 file changed, 20 insertions(+), 25 deletions(-)
Comments
On Sat, 10 Feb 2024 at 12:36, <alexs@kernel.org> wrote:
>
> From: Alex Shi <alexs@kernel.org>
>
> sched_use_asym_prio() and sched_asym_prefer() are used together in various
> places. Consolidate them into a single function sched_asym().
>
> The existing sched_group_asym() is only used when collecting statistics
nit: The existing sched_asym()
> of a scheduling group. Rename it as sched_group_asym(), and remove the
> obsolete function description.
>
> This makes the code easier to read. No functional changes.
>
> Tested-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
> Signed-off-by: Alex Shi <alexs@kernel.org>
> Cc: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
> Cc: Valentin Schneider <vschneid@redhat.com>
> Cc: Vincent Guittot <vincent.guittot@linaro.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Reviewed-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
> ---
> kernel/sched/fair.c | 45 ++++++++++++++++++++-------------------------
> 1 file changed, 20 insertions(+), 25 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 607dc310b355..426eda9eda57 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -9746,8 +9746,18 @@ static bool sched_use_asym_prio(struct sched_domain *sd, int cpu)
> return sd->flags & SD_SHARE_CPUCAPACITY || is_core_idle(cpu);
> }
>
> +static inline bool sched_asym(struct sched_domain *sd, int dst_cpu, int src_cpu)
> +{
> + /*
> + * First check if @dst_cpu can do asym_packing load balance. Only do it
> + * if it has higher priority than @src_cpu.
> + */
> + return sched_use_asym_prio(sd, dst_cpu) &&
> + sched_asym_prefer(dst_cpu, src_cpu);
> +}
> +
> /**
> - * sched_asym - Check if the destination CPU can do asym_packing load balance
> + * sched_group_asym - Check if the destination CPU can do asym_packing balance
> * @env: The load balancing environment
> * @sgs: Load-balancing statistics of the candidate busiest group
> * @group: The candidate busiest group
> @@ -9755,34 +9765,21 @@ static bool sched_use_asym_prio(struct sched_domain *sd, int cpu)
> * @env::dst_cpu can do asym_packing if it has higher priority than the
> * preferred CPU of @group.
> *
> - * SMT is a special case. If we are balancing load between cores, @env::dst_cpu
> - * can do asym_packing balance only if all its SMT siblings are idle. Also, it
> - * can only do it if @group is an SMT group and has exactly on busy CPU. Larger
> - * imbalances in the number of CPUS are dealt with in find_busiest_group().
> - *
> - * If we are balancing load within an SMT core, or at PKG domain level, always
> - * proceed.
> - *
> * Return: true if @env::dst_cpu can do with asym_packing load balance. False
> * otherwise.
> */
> static inline bool
> -sched_asym(struct lb_env *env, struct sg_lb_stats *sgs, struct sched_group *group)
> +sched_group_asym(struct lb_env *env, struct sg_lb_stats *sgs, struct sched_group *group)
> {
> - /* Ensure that the whole local core is idle, if applicable. */
> - if (!sched_use_asym_prio(env->sd, env->dst_cpu))
> - return false;
> -
> /*
> - * CPU priorities does not make sense for SMT cores with more than one
> + * CPU priorities do not make sense for SMT cores with more than one
> * busy sibling.
> */
> - if (group->flags & SD_SHARE_CPUCAPACITY) {
> - if (sgs->group_weight - sgs->idle_cpus != 1)
> - return false;
> - }
> + if ((group->flags & SD_SHARE_CPUCAPACITY) &&
> + (sgs->group_weight - sgs->idle_cpus != 1))
> + return false;
>
> - return sched_asym_prefer(env->dst_cpu, group->asym_prefer_cpu);
> + return sched_asym(env->sd, env->dst_cpu, group->asym_prefer_cpu);
> }
>
> /* One group has more than one SMT CPU while the other group does not */
> @@ -9938,7 +9935,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
> /* 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_asym(env, sgs, group)) {
> + sched_group_asym(env, sgs, group)) {
> sgs->group_asym_packing = 1;
> }
>
> @@ -11037,8 +11034,7 @@ static struct rq *find_busiest_queue(struct lb_env *env,
> * SMT cores with more than one busy sibling.
> */
> if ((env->sd->flags & SD_ASYM_PACKING) &&
> - sched_use_asym_prio(env->sd, i) &&
> - sched_asym_prefer(i, env->dst_cpu) &&
> + sched_asym(env->sd, i, env->dst_cpu) &&
> nr_running == 1)
> continue;
>
> @@ -11908,8 +11904,7 @@ static void nohz_balancer_kick(struct rq *rq)
> * preferred CPU must be idle.
> */
> for_each_cpu_and(i, sched_domain_span(sd), nohz.idle_cpus_mask) {
> - if (sched_use_asym_prio(sd, i) &&
> - sched_asym_prefer(i, cpu)) {
> + if (sched_asym(sd, i, cpu)) {
> flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
> goto unlock;
> }
> --
> 2.43.0
>
On 2/14/24 12:51 AM, Vincent Guittot wrote:
> On Sat, 10 Feb 2024 at 12:36, <alexs@kernel.org> wrote:
>>
>> From: Alex Shi <alexs@kernel.org>
>>
>> sched_use_asym_prio() and sched_asym_prefer() are used together in various
>> places. Consolidate them into a single function sched_asym().
>>
>> The existing sched_group_asym() is only used when collecting statistics
>
> nit: The existing sched_asym()
Hi Vincent,
Thanks for all reviewing. Do I need to update this for next version? or just fix it during merge?
Alex
>
>> of a scheduling group. Rename it as sched_group_asym(), and remove the
>> obsolete function description.
>>
>> This makes the code easier to read. No functional changes.
>>
>> Tested-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
>> Signed-off-by: Alex Shi <alexs@kernel.org>
>> Cc: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
>> Cc: Valentin Schneider <vschneid@redhat.com>
>> Cc: Vincent Guittot <vincent.guittot@linaro.org>
>> Cc: Peter Zijlstra <peterz@infradead.org>
>> Cc: Ingo Molnar <mingo@redhat.com>
>> Reviewed-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
>
> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
>
>> ---
>> kernel/sched/fair.c | 45 ++++++++++++++++++++-------------------------
>> 1 file changed, 20 insertions(+), 25 deletions(-)
>>
>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>> index 607dc310b355..426eda9eda57 100644
>> --- a/kernel/sched/fair.c
>> +++ b/kernel/sched/fair.c
>> @@ -9746,8 +9746,18 @@ static bool sched_use_asym_prio(struct sched_domain *sd, int cpu)
>> return sd->flags & SD_SHARE_CPUCAPACITY || is_core_idle(cpu);
>> }
>>
>> +static inline bool sched_asym(struct sched_domain *sd, int dst_cpu, int src_cpu)
>> +{
>> + /*
>> + * First check if @dst_cpu can do asym_packing load balance. Only do it
>> + * if it has higher priority than @src_cpu.
>> + */
>> + return sched_use_asym_prio(sd, dst_cpu) &&
>> + sched_asym_prefer(dst_cpu, src_cpu);
>> +}
>> +
>> /**
>> - * sched_asym - Check if the destination CPU can do asym_packing load balance
>> + * sched_group_asym - Check if the destination CPU can do asym_packing balance
>> * @env: The load balancing environment
>> * @sgs: Load-balancing statistics of the candidate busiest group
>> * @group: The candidate busiest group
>> @@ -9755,34 +9765,21 @@ static bool sched_use_asym_prio(struct sched_domain *sd, int cpu)
>> * @env::dst_cpu can do asym_packing if it has higher priority than the
>> * preferred CPU of @group.
>> *
>> - * SMT is a special case. If we are balancing load between cores, @env::dst_cpu
>> - * can do asym_packing balance only if all its SMT siblings are idle. Also, it
>> - * can only do it if @group is an SMT group and has exactly on busy CPU. Larger
>> - * imbalances in the number of CPUS are dealt with in find_busiest_group().
>> - *
>> - * If we are balancing load within an SMT core, or at PKG domain level, always
>> - * proceed.
>> - *
>> * Return: true if @env::dst_cpu can do with asym_packing load balance. False
>> * otherwise.
>> */
>> static inline bool
>> -sched_asym(struct lb_env *env, struct sg_lb_stats *sgs, struct sched_group *group)
>> +sched_group_asym(struct lb_env *env, struct sg_lb_stats *sgs, struct sched_group *group)
>> {
>> - /* Ensure that the whole local core is idle, if applicable. */
>> - if (!sched_use_asym_prio(env->sd, env->dst_cpu))
>> - return false;
>> -
>> /*
>> - * CPU priorities does not make sense for SMT cores with more than one
>> + * CPU priorities do not make sense for SMT cores with more than one
>> * busy sibling.
>> */
>> - if (group->flags & SD_SHARE_CPUCAPACITY) {
>> - if (sgs->group_weight - sgs->idle_cpus != 1)
>> - return false;
>> - }
>> + if ((group->flags & SD_SHARE_CPUCAPACITY) &&
>> + (sgs->group_weight - sgs->idle_cpus != 1))
>> + return false;
>>
>> - return sched_asym_prefer(env->dst_cpu, group->asym_prefer_cpu);
>> + return sched_asym(env->sd, env->dst_cpu, group->asym_prefer_cpu);
>> }
>>
>> /* One group has more than one SMT CPU while the other group does not */
>> @@ -9938,7 +9935,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
>> /* 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_asym(env, sgs, group)) {
>> + sched_group_asym(env, sgs, group)) {
>> sgs->group_asym_packing = 1;
>> }
>>
>> @@ -11037,8 +11034,7 @@ static struct rq *find_busiest_queue(struct lb_env *env,
>> * SMT cores with more than one busy sibling.
>> */
>> if ((env->sd->flags & SD_ASYM_PACKING) &&
>> - sched_use_asym_prio(env->sd, i) &&
>> - sched_asym_prefer(i, env->dst_cpu) &&
>> + sched_asym(env->sd, i, env->dst_cpu) &&
>> nr_running == 1)
>> continue;
>>
>> @@ -11908,8 +11904,7 @@ static void nohz_balancer_kick(struct rq *rq)
>> * preferred CPU must be idle.
>> */
>> for_each_cpu_and(i, sched_domain_span(sd), nohz.idle_cpus_mask) {
>> - if (sched_use_asym_prio(sd, i) &&
>> - sched_asym_prefer(i, cpu)) {
>> + if (sched_asym(sd, i, cpu)) {
>> flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
>> goto unlock;
>> }
>> --
>> 2.43.0
>>
@@ -9746,8 +9746,18 @@ static bool sched_use_asym_prio(struct sched_domain *sd, int cpu)
return sd->flags & SD_SHARE_CPUCAPACITY || is_core_idle(cpu);
}
+static inline bool sched_asym(struct sched_domain *sd, int dst_cpu, int src_cpu)
+{
+ /*
+ * First check if @dst_cpu can do asym_packing load balance. Only do it
+ * if it has higher priority than @src_cpu.
+ */
+ return sched_use_asym_prio(sd, dst_cpu) &&
+ sched_asym_prefer(dst_cpu, src_cpu);
+}
+
/**
- * sched_asym - Check if the destination CPU can do asym_packing load balance
+ * sched_group_asym - Check if the destination CPU can do asym_packing balance
* @env: The load balancing environment
* @sgs: Load-balancing statistics of the candidate busiest group
* @group: The candidate busiest group
@@ -9755,34 +9765,21 @@ static bool sched_use_asym_prio(struct sched_domain *sd, int cpu)
* @env::dst_cpu can do asym_packing if it has higher priority than the
* preferred CPU of @group.
*
- * SMT is a special case. If we are balancing load between cores, @env::dst_cpu
- * can do asym_packing balance only if all its SMT siblings are idle. Also, it
- * can only do it if @group is an SMT group and has exactly on busy CPU. Larger
- * imbalances in the number of CPUS are dealt with in find_busiest_group().
- *
- * If we are balancing load within an SMT core, or at PKG domain level, always
- * proceed.
- *
* Return: true if @env::dst_cpu can do with asym_packing load balance. False
* otherwise.
*/
static inline bool
-sched_asym(struct lb_env *env, struct sg_lb_stats *sgs, struct sched_group *group)
+sched_group_asym(struct lb_env *env, struct sg_lb_stats *sgs, struct sched_group *group)
{
- /* Ensure that the whole local core is idle, if applicable. */
- if (!sched_use_asym_prio(env->sd, env->dst_cpu))
- return false;
-
/*
- * CPU priorities does not make sense for SMT cores with more than one
+ * CPU priorities do not make sense for SMT cores with more than one
* busy sibling.
*/
- if (group->flags & SD_SHARE_CPUCAPACITY) {
- if (sgs->group_weight - sgs->idle_cpus != 1)
- return false;
- }
+ if ((group->flags & SD_SHARE_CPUCAPACITY) &&
+ (sgs->group_weight - sgs->idle_cpus != 1))
+ return false;
- return sched_asym_prefer(env->dst_cpu, group->asym_prefer_cpu);
+ return sched_asym(env->sd, env->dst_cpu, group->asym_prefer_cpu);
}
/* One group has more than one SMT CPU while the other group does not */
@@ -9938,7 +9935,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
/* 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_asym(env, sgs, group)) {
+ sched_group_asym(env, sgs, group)) {
sgs->group_asym_packing = 1;
}
@@ -11037,8 +11034,7 @@ static struct rq *find_busiest_queue(struct lb_env *env,
* SMT cores with more than one busy sibling.
*/
if ((env->sd->flags & SD_ASYM_PACKING) &&
- sched_use_asym_prio(env->sd, i) &&
- sched_asym_prefer(i, env->dst_cpu) &&
+ sched_asym(env->sd, i, env->dst_cpu) &&
nr_running == 1)
continue;
@@ -11908,8 +11904,7 @@ static void nohz_balancer_kick(struct rq *rq)
* preferred CPU must be idle.
*/
for_each_cpu_and(i, sched_domain_span(sd), nohz.idle_cpus_mask) {
- if (sched_use_asym_prio(sd, i) &&
- sched_asym_prefer(i, cpu)) {
+ if (sched_asym(sd, i, cpu)) {
flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
goto unlock;
}