forked from Minki/linux
sched: Refactor the power savings balance code
Impact: cleanup Create seperate helper functions to initialize the power-savings-balance related variables, to update them and to check if we have a scope for performing power-savings balance. Add no-op inline functions for the !(CONFIG_SCHED_MC || CONFIG_SCHED_SMT) case. This will eliminate all the #ifdef jungle in find_busiest_group() and the other helper functions. Signed-off-by: Gautham R Shenoy <ego@in.ibm.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: "Balbir Singh" <balbir@in.ibm.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: "Dhaval Giani" <dhaval@linux.vnet.ibm.com> Cc: Bharata B Rao <bharata@linux.vnet.ibm.com> Cc: "Vaidyanathan Srinivasan" <svaidy@linux.vnet.ibm.com> LKML-Reference: <20090325091422.13992.73616.stgit@sofia.in.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Gautham R Shenoy
Ingo Molnar
parent
a021dc0337
commit
c071df1852
236
kernel/sched.c
236
kernel/sched.c
@ -3270,6 +3270,151 @@ static inline int get_sd_load_idx(struct sched_domain *sd,
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}
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#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
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/**
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* init_sd_power_savings_stats - Initialize power savings statistics for
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* the given sched_domain, during load balancing.
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*
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* @sd: Sched domain whose power-savings statistics are to be initialized.
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* @sds: Variable containing the statistics for sd.
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* @idle: Idle status of the CPU at which we're performing load-balancing.
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*/
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static inline void init_sd_power_savings_stats(struct sched_domain *sd,
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struct sd_lb_stats *sds, enum cpu_idle_type idle)
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{
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/*
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* Busy processors will not participate in power savings
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* balance.
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*/
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if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
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sds->power_savings_balance = 0;
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else {
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sds->power_savings_balance = 1;
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sds->min_nr_running = ULONG_MAX;
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sds->leader_nr_running = 0;
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}
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}
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/**
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* update_sd_power_savings_stats - Update the power saving stats for a
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* sched_domain while performing load balancing.
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*
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* @group: sched_group belonging to the sched_domain under consideration.
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* @sds: Variable containing the statistics of the sched_domain
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* @local_group: Does group contain the CPU for which we're performing
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* load balancing ?
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* @sgs: Variable containing the statistics of the group.
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*/
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static inline void update_sd_power_savings_stats(struct sched_group *group,
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struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
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{
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if (!sds->power_savings_balance)
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return;
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/*
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* If the local group is idle or completely loaded
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* no need to do power savings balance at this domain
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*/
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if (local_group && (sds->this_nr_running >= sgs->group_capacity ||
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!sds->this_nr_running))
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sds->power_savings_balance = 0;
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/*
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* If a group is already running at full capacity or idle,
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* don't include that group in power savings calculations
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*/
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if (!sds->power_savings_balance ||
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sgs->sum_nr_running >= sgs->group_capacity ||
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!sgs->sum_nr_running)
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return;
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/*
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* Calculate the group which has the least non-idle load.
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* This is the group from where we need to pick up the load
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* for saving power
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*/
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if ((sgs->sum_nr_running < sds->min_nr_running) ||
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(sgs->sum_nr_running == sds->min_nr_running &&
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group_first_cpu(group) > group_first_cpu(sds->group_min))) {
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sds->group_min = group;
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sds->min_nr_running = sgs->sum_nr_running;
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sds->min_load_per_task = sgs->sum_weighted_load /
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sgs->sum_nr_running;
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}
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/*
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* Calculate the group which is almost near its
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* capacity but still has some space to pick up some load
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* from other group and save more power
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*/
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if (sgs->sum_nr_running > sgs->group_capacity - 1)
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return;
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if (sgs->sum_nr_running > sds->leader_nr_running ||
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(sgs->sum_nr_running == sds->leader_nr_running &&
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group_first_cpu(group) < group_first_cpu(sds->group_leader))) {
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sds->group_leader = group;
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sds->leader_nr_running = sgs->sum_nr_running;
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}
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}
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/**
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* check_power_save_busiest_group - Check if we have potential to perform
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* some power-savings balance. If yes, set the busiest group to be
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* the least loaded group in the sched_domain, so that it's CPUs can
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* be put to idle.
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*
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* @sds: Variable containing the statistics of the sched_domain
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* under consideration.
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* @this_cpu: Cpu at which we're currently performing load-balancing.
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* @imbalance: Variable to store the imbalance.
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*
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* Returns 1 if there is potential to perform power-savings balance.
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* Else returns 0.
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*/
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static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
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int this_cpu, unsigned long *imbalance)
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{
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if (!sds->power_savings_balance)
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return 0;
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if (sds->this != sds->group_leader ||
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sds->group_leader == sds->group_min)
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return 0;
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*imbalance = sds->min_load_per_task;
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sds->busiest = sds->group_min;
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if (sched_mc_power_savings >= POWERSAVINGS_BALANCE_WAKEUP) {
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cpu_rq(this_cpu)->rd->sched_mc_preferred_wakeup_cpu =
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group_first_cpu(sds->group_leader);
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}
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return 1;
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}
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#else /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
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static inline void init_sd_power_savings_stats(struct sched_domain *sd,
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struct sd_lb_stats *sds, enum cpu_idle_type idle)
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{
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return;
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}
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static inline void update_sd_power_savings_stats(struct sched_group *group,
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struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
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{
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return;
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}
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static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
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int this_cpu, unsigned long *imbalance)
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{
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return 0;
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}
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#endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
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/**
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* update_sg_lb_stats - Update sched_group's statistics for load balancing.
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* @group: sched_group whose statistics are to be updated.
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@ -3385,19 +3530,7 @@ static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu,
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struct sg_lb_stats sgs;
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int load_idx;
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#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
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/*
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* Busy processors will not participate in power savings
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* balance.
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*/
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if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
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sds->power_savings_balance = 0;
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else {
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sds->power_savings_balance = 1;
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sds->min_nr_running = ULONG_MAX;
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sds->leader_nr_running = 0;
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}
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#endif
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init_sd_power_savings_stats(sd, sds, idle);
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load_idx = get_sd_load_idx(sd, idle);
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do {
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@ -3430,61 +3563,7 @@ static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu,
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sds->group_imb = sgs.group_imb;
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}
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#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
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if (!sds->power_savings_balance)
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goto group_next;
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/*
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* If the local group is idle or completely loaded
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* no need to do power savings balance at this domain
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*/
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if (local_group &&
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(sds->this_nr_running >= sgs.group_capacity ||
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!sds->this_nr_running))
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sds->power_savings_balance = 0;
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/*
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* If a group is already running at full capacity or idle,
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* don't include that group in power savings calculations
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*/
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if (!sds->power_savings_balance ||
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sgs.sum_nr_running >= sgs.group_capacity ||
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!sgs.sum_nr_running)
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goto group_next;
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/*
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* Calculate the group which has the least non-idle load.
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* This is the group from where we need to pick up the load
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* for saving power
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*/
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if ((sgs.sum_nr_running < sds->min_nr_running) ||
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(sgs.sum_nr_running == sds->min_nr_running &&
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group_first_cpu(group) >
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group_first_cpu(sds->group_min))) {
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sds->group_min = group;
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sds->min_nr_running = sgs.sum_nr_running;
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sds->min_load_per_task = sgs.sum_weighted_load /
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sgs.sum_nr_running;
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}
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/*
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* Calculate the group which is almost near its
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* capacity but still has some space to pick up some load
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* from other group and save more power
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*/
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if (sgs.sum_nr_running > sgs.group_capacity - 1)
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goto group_next;
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if (sgs.sum_nr_running > sds->leader_nr_running ||
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(sgs.sum_nr_running == sds->leader_nr_running &&
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group_first_cpu(group) <
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group_first_cpu(sds->group_leader))) {
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sds->group_leader = group;
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sds->leader_nr_running = sgs.sum_nr_running;
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}
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group_next:
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#endif
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update_sd_power_savings_stats(group, sds, local_group, &sgs);
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group = group->next;
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} while (group != sd->groups);
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@ -3655,21 +3734,12 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
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return sds.busiest;
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out_balanced:
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#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
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if (!sds.power_savings_balance)
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goto ret;
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if (sds.this != sds.group_leader || sds.group_leader == sds.group_min)
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goto ret;
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*imbalance = sds.min_load_per_task;
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if (sched_mc_power_savings >= POWERSAVINGS_BALANCE_WAKEUP) {
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cpu_rq(this_cpu)->rd->sched_mc_preferred_wakeup_cpu =
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group_first_cpu(sds.group_leader);
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}
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return sds.group_min;
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#endif
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/*
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* There is no obvious imbalance. But check if we can do some balancing
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* to save power.
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*/
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if (check_power_save_busiest_group(&sds, this_cpu, imbalance))
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return sds.busiest;
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ret:
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*imbalance = 0;
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return NULL;
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