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sched: Refactor the power savings balance code

Browse source 
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 2009-03-25 14:44:22 +05:30 committed by Ingo Molnar
parent a021dc0337
commit c071df1852
1 changed files with 153 additions and 83 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

236
kernel/sched.c
View file

@ -3270,6 +3270,151 @@ static inline int get_sd_load_idx(struct sched_domain *sd,
}
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
/**
* init_sd_power_savings_stats - Initialize power savings statistics for
* the given sched_domain, during load balancing.
*
* @sd: Sched domain whose power-savings statistics are to be initialized.
* @sds: Variable containing the statistics for sd.
* @idle: Idle status of the CPU at which we're performing load-balancing.
*/
static inline void init_sd_power_savings_stats(struct sched_domain *sd,
struct sd_lb_stats *sds, enum cpu_idle_type idle)
{
/*
* Busy processors will not participate in power savings
* balance.
*/
if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
sds->power_savings_balance = 0;
else {
sds->power_savings_balance = 1;
sds->min_nr_running = ULONG_MAX;
sds->leader_nr_running = 0;
}
}
/**
* update_sd_power_savings_stats - Update the power saving stats for a
* sched_domain while performing load balancing.
*
* @group: sched_group belonging to the sched_domain under consideration.
* @sds: Variable containing the statistics of the sched_domain
* @local_group: Does group contain the CPU for which we're performing
* load balancing ?
* @sgs: Variable containing the statistics of the group.
*/
static inline void update_sd_power_savings_stats(struct sched_group *group,
struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
{
if (!sds->power_savings_balance)
return;
/*
* If the local group is idle or completely loaded
* no need to do power savings balance at this domain
*/
if (local_group && (sds->this_nr_running >= sgs->group_capacity ||
!sds->this_nr_running))
sds->power_savings_balance = 0;
/*
* If a group is already running at full capacity or idle,
* don't include that group in power savings calculations
*/
if (!sds->power_savings_balance ||
sgs->sum_nr_running >= sgs->group_capacity ||
!sgs->sum_nr_running)
return;
/*
* Calculate the group which has the least non-idle load.
* This is the group from where we need to pick up the load
* for saving power
*/
if ((sgs->sum_nr_running < sds->min_nr_running) ||
(sgs->sum_nr_running == sds->min_nr_running &&
group_first_cpu(group) > group_first_cpu(sds->group_min))) {
sds->group_min = group;
sds->min_nr_running = sgs->sum_nr_running;
sds->min_load_per_task = sgs->sum_weighted_load /
sgs->sum_nr_running;
}
/*
* Calculate the group which is almost near its
* capacity but still has some space to pick up some load
* from other group and save more power
*/
if (sgs->sum_nr_running > sgs->group_capacity - 1)
return;
if (sgs->sum_nr_running > sds->leader_nr_running ||
(sgs->sum_nr_running == sds->leader_nr_running &&
group_first_cpu(group) < group_first_cpu(sds->group_leader))) {
sds->group_leader = group;
sds->leader_nr_running = sgs->sum_nr_running;
}
}
/**
* check_power_save_busiest_group - Check if we have potential to perform
* some power-savings balance. If yes, set the busiest group to be
* the least loaded group in the sched_domain, so that it's CPUs can
* be put to idle.
*
* @sds: Variable containing the statistics of the sched_domain
* under consideration.
* @this_cpu: Cpu at which we're currently performing load-balancing.
* @imbalance: Variable to store the imbalance.
*
* Returns 1 if there is potential to perform power-savings balance.
* Else returns 0.
*/
static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
int this_cpu, unsigned long *imbalance)
{
if (!sds->power_savings_balance)
return 0;
if (sds->this != sds->group_leader ||
sds->group_leader == sds->group_min)
return 0;
*imbalance = sds->min_load_per_task;
sds->busiest = sds->group_min;
if (sched_mc_power_savings >= POWERSAVINGS_BALANCE_WAKEUP) {
cpu_rq(this_cpu)->rd->sched_mc_preferred_wakeup_cpu =
group_first_cpu(sds->group_leader);
}
return 1;
}
#else /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
static inline void init_sd_power_savings_stats(struct sched_domain *sd,
struct sd_lb_stats *sds, enum cpu_idle_type idle)
{
return;
}
static inline void update_sd_power_savings_stats(struct sched_group *group,
struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
{
return;
}
static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
int this_cpu, unsigned long *imbalance)
{
return 0;
}
#endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
/**
* update_sg_lb_stats - Update sched_group's statistics for load balancing.
* @group: sched_group whose statistics are to be updated.
@ -3385,19 +3530,7 @@ static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu,
struct sg_lb_stats sgs;
int load_idx;
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
/*
* Busy processors will not participate in power savings
* balance.
*/
if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
sds->power_savings_balance = 0;
else {
sds->power_savings_balance = 1;
sds->min_nr_running = ULONG_MAX;
sds->leader_nr_running = 0;
}
#endif
init_sd_power_savings_stats(sd, sds, idle);
load_idx = get_sd_load_idx(sd, idle);
do {
@ -3430,61 +3563,7 @@ static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu,
sds->group_imb = sgs.group_imb;
}
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
if (!sds->power_savings_balance)
goto group_next;
/*
* If the local group is idle or completely loaded
* no need to do power savings balance at this domain
*/
if (local_group &&
(sds->this_nr_running >= sgs.group_capacity ||
!sds->this_nr_running))
sds->power_savings_balance = 0;
/*
* If a group is already running at full capacity or idle,
* don't include that group in power savings calculations
*/
if (!sds->power_savings_balance ||
sgs.sum_nr_running >= sgs.group_capacity ||
!sgs.sum_nr_running)
goto group_next;
/*
* Calculate the group which has the least non-idle load.
* This is the group from where we need to pick up the load
* for saving power
*/
if ((sgs.sum_nr_running < sds->min_nr_running) ||
(sgs.sum_nr_running == sds->min_nr_running &&
group_first_cpu(group) >
group_first_cpu(sds->group_min))) {
sds->group_min = group;
sds->min_nr_running = sgs.sum_nr_running;
sds->min_load_per_task = sgs.sum_weighted_load /
sgs.sum_nr_running;
}
/*
* Calculate the group which is almost near its
* capacity but still has some space to pick up some load
* from other group and save more power
*/
if (sgs.sum_nr_running > sgs.group_capacity - 1)
goto group_next;
if (sgs.sum_nr_running > sds->leader_nr_running ||
(sgs.sum_nr_running == sds->leader_nr_running &&
group_first_cpu(group) <
group_first_cpu(sds->group_leader))) {
sds->group_leader = group;
sds->leader_nr_running = sgs.sum_nr_running;
}
group_next:
#endif
update_sd_power_savings_stats(group, sds, local_group, &sgs);
group = group->next;
} while (group != sd->groups);
@ -3655,21 +3734,12 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
return sds.busiest;
out_balanced:
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
if (!sds.power_savings_balance)
goto ret;
if (sds.this != sds.group_leader || sds.group_leader == sds.group_min)
goto ret;
*imbalance = sds.min_load_per_task;
if (sched_mc_power_savings >= POWERSAVINGS_BALANCE_WAKEUP) {
cpu_rq(this_cpu)->rd->sched_mc_preferred_wakeup_cpu =
group_first_cpu(sds.group_leader);
}
return sds.group_min;
#endif
/*
* There is no obvious imbalance. But check if we can do some balancing
* to save power.
*/
if (check_power_save_busiest_group(&sds, this_cpu, imbalance))
return sds.busiest;
ret:
*imbalance = 0;
return NULL;