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Subject[PATCH v4 1/5] sched: code cleanup - sd_power_saving_flags(), sd_balance_for_*_power()
Date
Combines the functions of sd_balance_for_mc/package_power() and
sd_power_saving_flags() into a single function.

Also add comments for various sched_domain levels.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
---

include/linux/sched.h | 65 +++++++++++++++++++++++-----------------------
include/linux/topology.h | 6 +---
2 files changed, 35 insertions(+), 36 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 1df4745..8aaf276 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -803,34 +803,45 @@ enum powersavings_balance_level {

extern int sched_mc_power_savings, sched_smt_power_savings;

-static inline int sd_balance_for_mc_power(void)
-{
- if (sched_smt_power_savings)
- return SD_POWERSAVINGS_BALANCE;
-
- return 0;
-}
-
-static inline int sd_balance_for_package_power(void)
-{
- if (sched_mc_power_savings | sched_smt_power_savings)
- return SD_POWERSAVINGS_BALANCE;
+enum sched_domain_level {
+ SD_LV_NONE = 0,
+ SD_LV_SIBLING, /* Represents the THREADS domain */
+ SD_LV_MC, /* Represents the CORES domain */
+ SD_LV_CPU, /* Represents the PACKAGE domain */
+ SD_LV_NODE, /* Represents the NODES domain */
+ SD_LV_ALLNODES,
+ SD_LV_MAX
+};

- return 0;
-}

-/*
- * Optimise SD flags for power savings:
- * SD_BALANCE_NEWIDLE helps agressive task consolidation and power savings.
- * Keep default SD flags if sched_{smt,mc}_power_saving=0
+/**
+ * sd_power_savings_flags: Returns the flags specific to power-aware-load
+ * balancing for a given sched_domain level
+ *
+ * @level: The sched_domain level for which the the power-aware-load balancing
+ * flags need to be set.
+ *
+ * This function helps in setting the flags for power-aware load balancing for
+ * a given sched_domain.
+ * - SD_POWERSAVINGS_BALANCE tells the load-balancer that power-aware
+ * load balancing is applicable at this domain.
+ *
+ * - SD_BALANCE_NEWIDLE helps aggressive task consolidation and
+ * power-savings.
+ *
+ * For more information on power aware scheduling, see the comment before
+ * find_busiest_group() in kernel/sched.c
*/

-static inline int sd_power_saving_flags(void)
+static inline int sd_power_saving_flags(enum sched_domain_level level)
{
- if (sched_mc_power_savings | sched_smt_power_savings)
- return SD_BALANCE_NEWIDLE;
+ if (level == SD_LV_MC && !sched_smt_power_savings)
+ return 0;
+ if (level == SD_LV_CPU &&
+ !(sched_mc_power_savings || sched_smt_power_savings))
+ return 0;

- return 0;
+ return SD_POWERSAVINGS_BALANCE | SD_BALANCE_NEWIDLE;
}

struct sched_group {
@@ -856,16 +867,6 @@ static inline struct cpumask *sched_group_cpus(struct sched_group *sg)
return to_cpumask(sg->cpumask);
}

-enum sched_domain_level {
- SD_LV_NONE = 0,
- SD_LV_SIBLING,
- SD_LV_MC,
- SD_LV_CPU,
- SD_LV_NODE,
- SD_LV_ALLNODES,
- SD_LV_MAX
-};
-
struct sched_domain_attr {
int relax_domain_level;
};
diff --git a/include/linux/topology.h b/include/linux/topology.h
index 7402c1a..2338388 100644
--- a/include/linux/topology.h
+++ b/include/linux/topology.h
@@ -121,8 +121,7 @@ int arch_update_cpu_topology(void);
| SD_WAKE_AFFINE \
| SD_WAKE_BALANCE \
| SD_SHARE_PKG_RESOURCES\
- | sd_balance_for_mc_power()\
- | sd_power_saving_flags(),\
+ | sd_power_saving_flags(SD_LV_MC),\
.last_balance = jiffies, \
.balance_interval = 1, \
}
@@ -147,8 +146,7 @@ int arch_update_cpu_topology(void);
| SD_BALANCE_FORK \
| SD_WAKE_AFFINE \
| SD_WAKE_BALANCE \
- | sd_balance_for_package_power()\
- | sd_power_saving_flags(),\
+ | sd_power_saving_flags(SD_LV_CPU),\
.last_balance = jiffies, \
.balance_interval = 1, \
}


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