[PATCH V3 0/10] sched: remove cpu_load

[PATCH V3 0/10] sched: remove cpu_load

[Alex Shi]

The cpu_load decays on time according past cpu load of rq. The sched_avg 
also decays tasks' load on time. Now we has 2 kind decay for cpu_load. 
That is a kind of redundancy. And increase the system load by decay 
calculation. This patch try to remove the cpu_load decay.

There are 5 load_idx used for cpu_load in sched_domain. busy_idx and 
idle_idx are not zero usually, but newidle_idx, wake_idx and forkexec_idx 
are all zero on every arch. A shortcut to remove cpu_Load decay in the first
patch. just one line patch for this change.

V3,
1, correct the wake_affine bias. Thanks for Morten's reminder!
2, replace source_load by weighted_cpuload for better function name meaning.

V2,
1, This version do some tuning on load bias of target load.
2, Got further to remove the cpu_load in rq.
3, Revert the patch 'Limit sd->*_idx range on sysctl' since no needs

Any testing/comments are appreciated.

This patch rebase on latest tip/master.
The git tree for this patchset at:
 git@github.com:alexshi/power-scheduling.git noload

[PATCH 01/10] sched: shortcut to remove load_idx

[Alex Shi]

Shortcut to remove rq->cpu_load[load_idx] effect in scheduler.
In five load idx, only busy_idx, idle_idx are not zero.
Newidle_idx, wake_idx and fork_idx are all zero in all archs.

So, change the idx to zero here can fully remove load_idx effect.

Signed-off-by: Alex Shi <alex.shi@linaro.org>
---
 kernel/sched/fair.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 235cfa7..4fcc3a3 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5908,7 +5908,7 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd
 	if (child && child->flags & SD_PREFER_SIBLING)
 		prefer_sibling = 1;
 
-	load_idx = get_sd_load_idx(env->sd, env->idle);
+	load_idx = 0;
 
 	do {
 		struct sg_lb_stats *sgs = &tmp_sgs;
-- 
1.8.1.2

[PATCH 02/10] sched: remove rq->cpu_load[load_idx] array

[Alex Shi]

Since load_idx effect removed in load balance, we don't need the
load_idx decays in scheduler. that will save some process in sched_tick
and others places.

Signed-off-by: Alex Shi <alex.shi@linaro.org>
---
 arch/ia64/include/asm/topology.h  |  5 ---
 arch/metag/include/asm/topology.h |  5 ---
 arch/tile/include/asm/topology.h  |  6 ---
 include/linux/sched.h             |  5 ---
 include/linux/topology.h          |  8 ----
 kernel/sched/core.c               | 58 +++++++-----------------
 kernel/sched/debug.c              |  6 +--
 kernel/sched/fair.c               | 79 +++++++++------------------------
 kernel/sched/proc.c               | 92 ++-------------------------------------
 kernel/sched/sched.h              |  3 +-
 10 files changed, 42 insertions(+), 225 deletions(-)

diff --git a/arch/ia64/include/asm/topology.h b/arch/ia64/include/asm/topology.h
index a2496e4..54e5b17 100644
--- a/arch/ia64/include/asm/topology.h
+++ b/arch/ia64/include/asm/topology.h
@@ -55,11 +55,6 @@ void build_cpu_to_node_map(void);
 	.busy_factor		= 64,			\
 	.imbalance_pct		= 125,			\
 	.cache_nice_tries	= 2,			\
-	.busy_idx		= 2,			\
-	.idle_idx		= 1,			\
-	.newidle_idx		= 0,			\
-	.wake_idx		= 0,			\
-	.forkexec_idx		= 0,			\
 	.flags			= SD_LOAD_BALANCE	\
 				| SD_BALANCE_NEWIDLE	\
 				| SD_BALANCE_EXEC	\
diff --git a/arch/metag/include/asm/topology.h b/arch/metag/include/asm/topology.h
index 8e9c0b3..d1d15cd 100644
--- a/arch/metag/include/asm/topology.h
+++ b/arch/metag/include/asm/topology.h
@@ -13,11 +13,6 @@
 	.busy_factor		= 32,			\
 	.imbalance_pct		= 125,			\
 	.cache_nice_tries	= 2,			\
-	.busy_idx		= 3,			\
-	.idle_idx		= 2,			\
-	.newidle_idx		= 0,			\
-	.wake_idx		= 0,			\
-	.forkexec_idx		= 0,			\
 	.flags			= SD_LOAD_BALANCE	\
 				| SD_BALANCE_FORK	\
 				| SD_BALANCE_EXEC	\
diff --git a/arch/tile/include/asm/topology.h b/arch/tile/include/asm/topology.h
index d15c0d8..05f6ffe 100644
--- a/arch/tile/include/asm/topology.h
+++ b/arch/tile/include/asm/topology.h
@@ -57,12 +57,6 @@ static inline const struct cpumask *cpumask_of_node(int node)
 	.busy_factor		= 64,					\
 	.imbalance_pct		= 125,					\
 	.cache_nice_tries	= 1,					\
-	.busy_idx		= 2,					\
-	.idle_idx		= 1,					\
-	.newidle_idx		= 0,					\
-	.wake_idx		= 0,					\
-	.forkexec_idx		= 0,					\
-									\
 	.flags			= 1*SD_LOAD_BALANCE			\
 				| 1*SD_BALANCE_NEWIDLE			\
 				| 1*SD_BALANCE_EXEC			\
diff --git a/include/linux/sched.h b/include/linux/sched.h
index c49a258..6c416c8 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -892,11 +892,6 @@ struct sched_domain {
 	unsigned int busy_factor;	/* less balancing by factor if busy */
 	unsigned int imbalance_pct;	/* No balance until over watermark */
 	unsigned int cache_nice_tries;	/* Leave cache hot tasks for # tries */
-	unsigned int busy_idx;
-	unsigned int idle_idx;
-	unsigned int newidle_idx;
-	unsigned int wake_idx;
-	unsigned int forkexec_idx;
 	unsigned int smt_gain;
 
 	int nohz_idle;			/* NOHZ IDLE status */
diff --git a/include/linux/topology.h b/include/linux/topology.h
index 12ae6ce..863fad3 100644
--- a/include/linux/topology.h
+++ b/include/linux/topology.h
@@ -121,9 +121,6 @@ int arch_update_cpu_topology(void);
 	.busy_factor		= 64,					\
 	.imbalance_pct		= 125,					\
 	.cache_nice_tries	= 1,					\
-	.busy_idx		= 2,					\
-	.wake_idx		= 0,					\
-	.forkexec_idx		= 0,					\
 									\
 	.flags			= 1*SD_LOAD_BALANCE			\
 				| 1*SD_BALANCE_NEWIDLE			\
@@ -151,11 +148,6 @@ int arch_update_cpu_topology(void);
 	.busy_factor		= 64,					\
 	.imbalance_pct		= 125,					\
 	.cache_nice_tries	= 1,					\
-	.busy_idx		= 2,					\
-	.idle_idx		= 1,					\
-	.newidle_idx		= 0,					\
-	.wake_idx		= 0,					\
-	.forkexec_idx		= 0,					\
 									\
 	.flags			= 1*SD_LOAD_BALANCE			\
 				| 1*SD_BALANCE_NEWIDLE			\
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fb9764f..ac2f10c 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4787,64 +4787,45 @@ static void sd_free_ctl_entry(struct ctl_table **tablep)
 	*tablep = NULL;
 }
 
-static int min_load_idx = 0;
-static int max_load_idx = CPU_LOAD_IDX_MAX-1;
-
 static void
 set_table_entry(struct ctl_table *entry,
 		const char *procname, void *data, int maxlen,
-		umode_t mode, proc_handler *proc_handler,
-		bool load_idx)
+		umode_t mode, proc_handler *proc_handler)
 {
 	entry->procname = procname;
 	entry->data = data;
 	entry->maxlen = maxlen;
 	entry->mode = mode;
 	entry->proc_handler = proc_handler;
-
-	if (load_idx) {
-		entry->extra1 = &min_load_idx;
-		entry->extra2 = &max_load_idx;
-	}
 }
 
 static struct ctl_table *
 sd_alloc_ctl_domain_table(struct sched_domain *sd)
 {
-	struct ctl_table *table = sd_alloc_ctl_entry(14);
+	struct ctl_table *table = sd_alloc_ctl_entry(9);
 
 	if (table == NULL)
 		return NULL;
 
 	set_table_entry(&table[0], "min_interval", &sd->min_interval,
-		sizeof(long), 0644, proc_doulongvec_minmax, false);
+		sizeof(long), 0644, proc_doulongvec_minmax);
 	set_table_entry(&table[1], "max_interval", &sd->max_interval,
-		sizeof(long), 0644, proc_doulongvec_minmax, false);
-	set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
-		sizeof(int), 0644, proc_dointvec_minmax, true);
-	set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
-		sizeof(int), 0644, proc_dointvec_minmax, true);
-	set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
-		sizeof(int), 0644, proc_dointvec_minmax, true);
-	set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
-		sizeof(int), 0644, proc_dointvec_minmax, true);
-	set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
-		sizeof(int), 0644, proc_dointvec_minmax, true);
-	set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
-		sizeof(int), 0644, proc_dointvec_minmax, false);
-	set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
-		sizeof(int), 0644, proc_dointvec_minmax, false);
-	set_table_entry(&table[9], "cache_nice_tries",
+		sizeof(long), 0644, proc_doulongvec_minmax);
+	set_table_entry(&table[2], "busy_factor", &sd->busy_factor,
+		sizeof(int), 0644, proc_dointvec_minmax);
+	set_table_entry(&table[3], "imbalance_pct", &sd->imbalance_pct,
+		sizeof(int), 0644, proc_dointvec_minmax);
+	set_table_entry(&table[4], "cache_nice_tries",
 		&sd->cache_nice_tries,
-		sizeof(int), 0644, proc_dointvec_minmax, false);
+		sizeof(int), 0644, proc_dointvec_minmax);
 	set_table_entry(&table[10], "flags", &sd->flags,
-		sizeof(int), 0644, proc_dointvec_minmax, false);
+		sizeof(int), 0644, proc_dointvec_minmax);
 	set_table_entry(&table[11], "max_newidle_lb_cost",
 		&sd->max_newidle_lb_cost,
-		sizeof(long), 0644, proc_doulongvec_minmax, false);
+		sizeof(long), 0644, proc_doulongvec_minmax);
 	set_table_entry(&table[12], "name", sd->name,
-		CORENAME_MAX_SIZE, 0444, proc_dostring, false);
-	/* &table[13] is terminator */
+		CORENAME_MAX_SIZE, 0444, proc_dostring);
+	/* &table[8] is terminator */
 
 	return table;
 }
@@ -5967,11 +5948,6 @@ sd_numa_init(struct sched_domain_topology_level *tl, int cpu)
 		.busy_factor		= 32,
 		.imbalance_pct		= 125,
 		.cache_nice_tries	= 2,
-		.busy_idx		= 3,
-		.idle_idx		= 2,
-		.newidle_idx		= 0,
-		.wake_idx		= 0,
-		.forkexec_idx		= 0,
 
 		.flags			= 1*SD_LOAD_BALANCE
 					| 1*SD_BALANCE_NEWIDLE
@@ -6721,7 +6697,7 @@ DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
 
 void __init sched_init(void)
 {
-	int i, j;
+	int i;
 	unsigned long alloc_size = 0, ptr;
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
@@ -6825,9 +6801,7 @@ void __init sched_init(void)
 		init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
 #endif
 
-		for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
-			rq->cpu_load[j] = 0;
-
+		rq->cpu_load = 0;
 		rq->last_load_update_tick = jiffies;
 
 #ifdef CONFIG_SMP
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index f3344c3..a24d549 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -303,11 +303,7 @@ do {									\
 	PN(next_balance);
 	SEQ_printf(m, "  .%-30s: %ld\n", "curr->pid", (long)(task_pid_nr(rq->curr)));
 	PN(clock);
-	P(cpu_load[0]);
-	P(cpu_load[1]);
-	P(cpu_load[2]);
-	P(cpu_load[3]);
-	P(cpu_load[4]);
+	P(cpu_load);
 #undef P
 #undef PN
 
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4fcc3a3..eeffe75 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1015,8 +1015,8 @@ bool should_numa_migrate_memory(struct task_struct *p, struct page * page,
 }
 
 static unsigned long weighted_cpuload(const int cpu);
-static unsigned long source_load(int cpu, int type);
-static unsigned long target_load(int cpu, int type);
+static unsigned long source_load(int cpu);
+static unsigned long target_load(int cpu);
 static unsigned long power_of(int cpu);
 static long effective_load(struct task_group *tg, int cpu, long wl, long wg);
 
@@ -3952,30 +3952,30 @@ static unsigned long weighted_cpuload(const int cpu)
  * We want to under-estimate the load of migration sources, to
  * balance conservatively.
  */
-static unsigned long source_load(int cpu, int type)
+static unsigned long source_load(int cpu)
 {
 	struct rq *rq = cpu_rq(cpu);
 	unsigned long total = weighted_cpuload(cpu);
 
-	if (type == 0 || !sched_feat(LB_BIAS))
+	if (!sched_feat(LB_BIAS))
 		return total;
 
-	return min(rq->cpu_load[type-1], total);
+	return min(rq->cpu_load, total);
 }
 
 /*
  * Return a high guess at the load of a migration-target cpu weighted
  * according to the scheduling class and "nice" value.
  */
-static unsigned long target_load(int cpu, int type)
+static unsigned long target_load(int cpu)
 {
 	struct rq *rq = cpu_rq(cpu);
 	unsigned long total = weighted_cpuload(cpu);
 
-	if (type == 0 || !sched_feat(LB_BIAS))
+	if (!sched_feat(LB_BIAS))
 		return total;
 
-	return max(rq->cpu_load[type-1], total);
+	return max(rq->cpu_load, total);
 }
 
 static unsigned long power_of(int cpu)
@@ -4175,7 +4175,7 @@ static int wake_wide(struct task_struct *p)
 static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
 {
 	s64 this_load, load;
-	int idx, this_cpu, prev_cpu;
+	int this_cpu, prev_cpu;
 	unsigned long tl_per_task;
 	struct task_group *tg;
 	unsigned long weight;
@@ -4188,11 +4188,10 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
 	if (wake_wide(p))
 		return 0;
 
-	idx	  = sd->wake_idx;
 	this_cpu  = smp_processor_id();
 	prev_cpu  = task_cpu(p);
-	load	  = source_load(prev_cpu, idx);
-	this_load = target_load(this_cpu, idx);
+	load	  = source_load(prev_cpu);
+	this_load = target_load(this_cpu);
 
 	/*
 	 * If sync wakeup then subtract the (maximum possible)
@@ -4248,7 +4247,7 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
 
 	if (balanced ||
 	    (this_load <= load &&
-	     this_load + target_load(prev_cpu, idx) <= tl_per_task)) {
+	     this_load + target_load(prev_cpu) <= tl_per_task)) {
 		/*
 		 * This domain has SD_WAKE_AFFINE and
 		 * p is cache cold in this domain, and
@@ -4267,17 +4266,12 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
  * domain.
  */
 static struct sched_group *
-find_idlest_group(struct sched_domain *sd, struct task_struct *p,
-		  int this_cpu, int sd_flag)
+find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
 {
 	struct sched_group *idlest = NULL, *group = sd->groups;
 	unsigned long min_load = ULONG_MAX, this_load = 0;
-	int load_idx = sd->forkexec_idx;
 	int imbalance = 100 + (sd->imbalance_pct-100)/2;
 
-	if (sd_flag & SD_BALANCE_WAKE)
-		load_idx = sd->wake_idx;
-
 	do {
 		unsigned long load, avg_load;
 		int local_group;
@@ -4297,9 +4291,9 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p,
 		for_each_cpu(i, sched_group_cpus(group)) {
 			/* Bias balancing toward cpus of our domain */
 			if (local_group)
-				load = source_load(i, load_idx);
+				load = source_load(i);
 			else
-				load = target_load(i, load_idx);
+				load = target_load(i);
 
 			avg_load += load;
 		}
@@ -4453,7 +4447,7 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
 			continue;
 		}
 
-		group = find_idlest_group(sd, p, cpu, sd_flag);
+		group = find_idlest_group(sd, p, cpu);
 		if (!group) {
 			sd = sd->child;
 			continue;
@@ -5495,34 +5489,6 @@ static inline void init_sd_lb_stats(struct sd_lb_stats *sds)
 	};
 }
 
-/**
- * get_sd_load_idx - Obtain the load index for a given sched domain.
- * @sd: The sched_domain whose load_idx is to be obtained.
- * @idle: The idle status of the CPU for whose sd load_idx is obtained.
- *
- * Return: The load index.
- */
-static inline int get_sd_load_idx(struct sched_domain *sd,
-					enum cpu_idle_type idle)
-{
-	int load_idx;
-
-	switch (idle) {
-	case CPU_NOT_IDLE:
-		load_idx = sd->busy_idx;
-		break;
-
-	case CPU_NEWLY_IDLE:
-		load_idx = sd->newidle_idx;
-		break;
-	default:
-		load_idx = sd->idle_idx;
-		break;
-	}
-
-	return load_idx;
-}
-
 static unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
 {
 	return SCHED_POWER_SCALE;
@@ -5770,12 +5736,11 @@ static inline int sg_capacity(struct lb_env *env, struct sched_group *group)
  * update_sg_lb_stats - Update sched_group's statistics for load balancing.
  * @env: The load balancing environment.
  * @group: sched_group whose statistics are to be updated.
- * @load_idx: Load index of sched_domain of this_cpu for load calc.
  * @local_group: Does group contain this_cpu.
  * @sgs: variable to hold the statistics for this group.
  */
 static inline void update_sg_lb_stats(struct lb_env *env,
-			struct sched_group *group, int load_idx,
+			struct sched_group *group,
 			int local_group, struct sg_lb_stats *sgs)
 {
 	unsigned long load;
@@ -5788,9 +5753,9 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 
 		/* Bias balancing toward cpus of our domain */
 		if (local_group)
-			load = target_load(i, load_idx);
+			load = target_load(i);
 		else
-			load = source_load(i, load_idx);
+			load = source_load(i);
 
 		sgs->group_load += load;
 		sgs->sum_nr_running += rq->nr_running;
@@ -5903,13 +5868,11 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd
 	struct sched_domain *child = env->sd->child;
 	struct sched_group *sg = env->sd->groups;
 	struct sg_lb_stats tmp_sgs;
-	int load_idx, prefer_sibling = 0;
+	int prefer_sibling = 0;
 
 	if (child && child->flags & SD_PREFER_SIBLING)
 		prefer_sibling = 1;
 
-	load_idx = 0;
-
 	do {
 		struct sg_lb_stats *sgs = &tmp_sgs;
 		int local_group;
@@ -5924,7 +5887,7 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd
 				update_group_power(env->sd, env->dst_cpu);
 		}
 
-		update_sg_lb_stats(env, sg, load_idx, local_group, sgs);
+		update_sg_lb_stats(env, sg, local_group, sgs);
 
 		if (local_group)
 			goto next_group;
diff --git a/kernel/sched/proc.c b/kernel/sched/proc.c
index 16f5a30..a2435c5 100644
--- a/kernel/sched/proc.c
+++ b/kernel/sched/proc.c
@@ -11,7 +11,7 @@
 unsigned long this_cpu_load(void)
 {
 	struct rq *this = this_rq();
-	return this->cpu_load[0];
+	return this->cpu_load;
 }
 
 
@@ -398,105 +398,19 @@ static void calc_load_account_active(struct rq *this_rq)
  * End of global load-average stuff
  */
 
-/*
- * The exact cpuload at various idx values, calculated at every tick would be
- * load = (2^idx - 1) / 2^idx * load + 1 / 2^idx * cur_load
- *
- * If a cpu misses updates for n-1 ticks (as it was idle) and update gets called
- * on nth tick when cpu may be busy, then we have:
- * load = ((2^idx - 1) / 2^idx)^(n-1) * load
- * load = (2^idx - 1) / 2^idx) * load + 1 / 2^idx * cur_load
- *
- * decay_load_missed() below does efficient calculation of
- * load = ((2^idx - 1) / 2^idx)^(n-1) * load
- * avoiding 0..n-1 loop doing load = ((2^idx - 1) / 2^idx) * load
- *
- * The calculation is approximated on a 128 point scale.
- * degrade_zero_ticks is the number of ticks after which load at any
- * particular idx is approximated to be zero.
- * degrade_factor is a precomputed table, a row for each load idx.
- * Each column corresponds to degradation factor for a power of two ticks,
- * based on 128 point scale.
- * Example:
- * row 2, col 3 (=12) says that the degradation at load idx 2 after
- * 8 ticks is 12/128 (which is an approximation of exact factor 3^8/4^8).
- *
- * With this power of 2 load factors, we can degrade the load n times
- * by looking at 1 bits in n and doing as many mult/shift instead of
- * n mult/shifts needed by the exact degradation.
- */
-#define DEGRADE_SHIFT		7
-static const unsigned char
-		degrade_zero_ticks[CPU_LOAD_IDX_MAX] = {0, 8, 32, 64, 128};
-static const unsigned char
-		degrade_factor[CPU_LOAD_IDX_MAX][DEGRADE_SHIFT + 1] = {
-					{0, 0, 0, 0, 0, 0, 0, 0},
-					{64, 32, 8, 0, 0, 0, 0, 0},
-					{96, 72, 40, 12, 1, 0, 0},
-					{112, 98, 75, 43, 15, 1, 0},
-					{120, 112, 98, 76, 45, 16, 2} };
 
 /*
- * Update cpu_load for any missed ticks, due to tickless idle. The backlog
- * would be when CPU is idle and so we just decay the old load without
- * adding any new load.
- */
-static unsigned long
-decay_load_missed(unsigned long load, unsigned long missed_updates, int idx)
-{
-	int j = 0;
-
-	if (!missed_updates)
-		return load;
-
-	if (missed_updates >= degrade_zero_ticks[idx])
-		return 0;
-
-	if (idx == 1)
-		return load >> missed_updates;
-
-	while (missed_updates) {
-		if (missed_updates % 2)
-			load = (load * degrade_factor[idx][j]) >> DEGRADE_SHIFT;
-
-		missed_updates >>= 1;
-		j++;
-	}
-	return load;
-}
-
-/*
- * Update rq->cpu_load[] statistics. This function is usually called every
+ * Update rq->cpu_load statistics. This function is usually called every
  * scheduler tick (TICK_NSEC). With tickless idle this will not be called
  * every tick. We fix it up based on jiffies.
  */
 static void __update_cpu_load(struct rq *this_rq, unsigned long this_load,
 			      unsigned long pending_updates)
 {
-	int i, scale;
-
 	this_rq->nr_load_updates++;
 
 	/* Update our load: */
-	this_rq->cpu_load[0] = this_load; /* Fasttrack for idx 0 */
-	for (i = 1, scale = 2; i < CPU_LOAD_IDX_MAX; i++, scale += scale) {
-		unsigned long old_load, new_load;
-
-		/* scale is effectively 1 << i now, and >> i divides by scale */
-
-		old_load = this_rq->cpu_load[i];
-		old_load = decay_load_missed(old_load, pending_updates - 1, i);
-		new_load = this_load;
-		/*
-		 * Round up the averaging division if load is increasing. This
-		 * prevents us from getting stuck on 9 if the load is 10, for
-		 * example.
-		 */
-		if (new_load > old_load)
-			new_load += scale - 1;
-
-		this_rq->cpu_load[i] = (old_load * (scale - 1) + new_load) >> i;
-	}
+	this_rq->cpu_load = this_load; /* Fasttrack for idx 0 */
 
 	sched_avg_update(this_rq);
 }
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 1bf34c2..5b2d4a1 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -517,8 +517,7 @@ struct rq {
 	unsigned int nr_numa_running;
 	unsigned int nr_preferred_running;
 #endif
-	#define CPU_LOAD_IDX_MAX 5
-	unsigned long cpu_load[CPU_LOAD_IDX_MAX];
+	unsigned long cpu_load;
 	unsigned long last_load_update_tick;
 #ifdef CONFIG_NO_HZ_COMMON
 	u64 nohz_stamp;
-- 
1.8.1.2

[PATCH 03/10] sched: clean up cpu_load update

[Alex Shi]

Since we don't decay the rq->cpu_load, so we don't need the
pending_updates. But we still want update rq->rt_avg, so
still keep rq->last_load_update_tick and func __update_cpu_load.

Signed-off-by: Alex Shi <alex.shi@linaro.org>
---
 kernel/sched/proc.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/kernel/sched/proc.c b/kernel/sched/proc.c
index a2435c5..057bb9b 100644
--- a/kernel/sched/proc.c
+++ b/kernel/sched/proc.c
@@ -404,8 +404,7 @@ static void calc_load_account_active(struct rq *this_rq)
  * scheduler tick (TICK_NSEC). With tickless idle this will not be called
  * every tick. We fix it up based on jiffies.
  */
-static void __update_cpu_load(struct rq *this_rq, unsigned long this_load,
-			      unsigned long pending_updates)
+static void __update_cpu_load(struct rq *this_rq, unsigned long this_load)
 {
 	this_rq->nr_load_updates++;
 
@@ -449,7 +448,6 @@ void update_idle_cpu_load(struct rq *this_rq)
 {
 	unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
 	unsigned long load = get_rq_runnable_load(this_rq);
-	unsigned long pending_updates;
 
 	/*
 	 * bail if there's load or we're actually up-to-date.
@@ -457,10 +455,9 @@ void update_idle_cpu_load(struct rq *this_rq)
 	if (load || curr_jiffies == this_rq->last_load_update_tick)
 		return;
 
-	pending_updates = curr_jiffies - this_rq->last_load_update_tick;
 	this_rq->last_load_update_tick = curr_jiffies;
 
-	__update_cpu_load(this_rq, load, pending_updates);
+	__update_cpu_load(this_rq, load);
 }
 
 /*
@@ -483,7 +480,7 @@ void update_cpu_load_nohz(void)
 		 * We were idle, this means load 0, the current load might be
 		 * !0 due to remote wakeups and the sort.
 		 */
-		__update_cpu_load(this_rq, 0, pending_updates);
+		__update_cpu_load(this_rq, 0);
 	}
 	raw_spin_unlock(&this_rq->lock);
 }
@@ -499,7 +496,7 @@ void update_cpu_load_active(struct rq *this_rq)
 	 * See the mess around update_idle_cpu_load() / update_cpu_load_nohz().
 	 */
 	this_rq->last_load_update_tick = jiffies;
-	__update_cpu_load(this_rq, load, 1);
+	__update_cpu_load(this_rq, load);
 
 	calc_load_account_active(this_rq);
 }
-- 
1.8.1.2

[PATCH 04/10] sched: unify imbalance bias for target group

[Alex Shi]

Old code considers the bias in source/target_load already. but still
use imbalance_pct as last check in idlest/busiest group finding. It is
also a kind of redundant job. If we bias imbalance in source/target_load,
we'd better not use imbalance_pct again.

After cpu_load array removed, it is nice time to unify the target bias
consideration. So I remove the imbalance_pct from last check and add the
live bias using.

On wake_affine, since all archs' wake_idx is 0, current logical is just
want to prefer current cpu. so we follows this logical. Just renaming the
target_load/source_load to wegithed_cpuload for more exact meaning.
Thanks for reminding from Morten!

Signed-off-by: Alex Shi <alex.shi@linaro.org>
---
 kernel/sched/fair.c | 32 +++++++++++++++-----------------
 1 file changed, 15 insertions(+), 17 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index eeffe75..5a3ea72 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1016,7 +1016,7 @@ bool should_numa_migrate_memory(struct task_struct *p, struct page * page,
 
 static unsigned long weighted_cpuload(const int cpu);
 static unsigned long source_load(int cpu);
-static unsigned long target_load(int cpu);
+static unsigned long target_load(int cpu, int imbalance_pct);
 static unsigned long power_of(int cpu);
 static long effective_load(struct task_group *tg, int cpu, long wl, long wg);
 
@@ -3967,7 +3967,7 @@ static unsigned long source_load(int cpu)
  * Return a high guess at the load of a migration-target cpu weighted
  * according to the scheduling class and "nice" value.
  */
-static unsigned long target_load(int cpu)
+static unsigned long target_load(int cpu, int imbalance_pct)
 {
 	struct rq *rq = cpu_rq(cpu);
 	unsigned long total = weighted_cpuload(cpu);
@@ -3975,6 +3975,11 @@ static unsigned long target_load(int cpu)
 	if (!sched_feat(LB_BIAS))
 		return total;
 
+	/*
+	 * Bias target load with imbalance_pct.
+	 */
+	total = total * imbalance_pct / 100;
+
 	return max(rq->cpu_load, total);
 }
 
@@ -4190,8 +4195,8 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
 
 	this_cpu  = smp_processor_id();
 	prev_cpu  = task_cpu(p);
-	load	  = source_load(prev_cpu);
-	this_load = target_load(this_cpu);
+	load	  = weighted_cpuload(prev_cpu);
+	this_load = weighted_cpuload(this_cpu);
 
 	/*
 	 * If sync wakeup then subtract the (maximum possible)
@@ -4247,7 +4252,7 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
 
 	if (balanced ||
 	    (this_load <= load &&
-	     this_load + target_load(prev_cpu) <= tl_per_task)) {
+		     this_load + weighted_cpuload(prev_cpu) <= tl_per_task)) {
 		/*
 		 * This domain has SD_WAKE_AFFINE and
 		 * p is cache cold in this domain, and
@@ -4293,7 +4298,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
 			if (local_group)
 				load = source_load(i);
 			else
-				load = target_load(i);
+				load = target_load(i, imbalance);
 
 			avg_load += load;
 		}
@@ -4309,7 +4314,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
 		}
 	} while (group = group->next, group != sd->groups);
 
-	if (!idlest || 100*this_load < imbalance*min_load)
+	if (!idlest || this_load < min_load)
 		return NULL;
 	return idlest;
 }
@@ -5745,6 +5750,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 {
 	unsigned long load;
 	int i;
+	int bias = 100 + (env->sd->imbalance_pct - 100) / 2;
 
 	memset(sgs, 0, sizeof(*sgs));
 
@@ -5752,8 +5758,8 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 		struct rq *rq = cpu_rq(i);
 
 		/* Bias balancing toward cpus of our domain */
-		if (local_group)
-			load = target_load(i);
+		if (local_group && env->idle != CPU_IDLE)
+			load = target_load(i, bias);
 		else
 			load = source_load(i);
 
@@ -6193,14 +6199,6 @@ static struct sched_group *find_busiest_group(struct lb_env *env)
 		if ((local->idle_cpus < busiest->idle_cpus) &&
 		    busiest->sum_nr_running <= busiest->group_weight)
 			goto out_balanced;
-	} else {
-		/*
-		 * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use
-		 * imbalance_pct to be conservative.
-		 */
-		if (100 * busiest->avg_load <=
-				env->sd->imbalance_pct * local->avg_load)
-			goto out_balanced;
 	}
 
 force_balance:
-- 
1.8.1.2

[PATCH 05/10] sched: rewrite update_cpu_load_nohz

[Alex Shi]

After change to sched_avg, the cpu load in idle exit was decayed.
So, it maybe near zero if waking a long time sleep task, or, a full
non-decay load if waking a new forked task. Then, we can use it to
reflect the cpu load, don't need to pretend 0.

Signed-off-by: Alex Shi <alex.shi@linaro.org>
---
 kernel/sched/proc.c | 19 ++-----------------
 1 file changed, 2 insertions(+), 17 deletions(-)

diff --git a/kernel/sched/proc.c b/kernel/sched/proc.c
index 057bb9b..383c4ba 100644
--- a/kernel/sched/proc.c
+++ b/kernel/sched/proc.c
@@ -461,28 +461,13 @@ void update_idle_cpu_load(struct rq *this_rq)
 }
 
 /*
- * Called from tick_nohz_idle_exit() -- try and fix up the ticks we missed.
+ * Called from tick_nohz_idle_exit()
  */
 void update_cpu_load_nohz(void)
 {
 	struct rq *this_rq = this_rq();
-	unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
-	unsigned long pending_updates;
-
-	if (curr_jiffies == this_rq->last_load_update_tick)
-		return;
 
-	raw_spin_lock(&this_rq->lock);
-	pending_updates = curr_jiffies - this_rq->last_load_update_tick;
-	if (pending_updates) {
-		this_rq->last_load_update_tick = curr_jiffies;
-		/*
-		 * We were idle, this means load 0, the current load might be
-		 * !0 due to remote wakeups and the sort.
-		 */
-		__update_cpu_load(this_rq, 0);
-	}
-	raw_spin_unlock(&this_rq->lock);
+	update_idle_cpu_load(this_rq);
 }
 #endif /* CONFIG_NO_HZ */
 
-- 
1.8.1.2

[PATCH 06/10] sched: clean up source_load/target_load

[Alex Shi]

Don't need 'rq' variable now.

Signed-off-by: Alex Shi <alex.shi@linaro.org>
---
 kernel/sched/fair.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 5a3ea72..d91d925 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3954,13 +3954,7 @@ static unsigned long weighted_cpuload(const int cpu)
  */
 static unsigned long source_load(int cpu)
 {
-	struct rq *rq = cpu_rq(cpu);
-	unsigned long total = weighted_cpuload(cpu);
-
-	if (!sched_feat(LB_BIAS))
-		return total;
-
-	return min(rq->cpu_load, total);
+	return weighted_cpuload(cpu);
 }
 
 /*
@@ -3969,7 +3963,6 @@ static unsigned long source_load(int cpu)
  */
 static unsigned long target_load(int cpu, int imbalance_pct)
 {
-	struct rq *rq = cpu_rq(cpu);
 	unsigned long total = weighted_cpuload(cpu);
 
 	if (!sched_feat(LB_BIAS))
@@ -3978,9 +3971,7 @@ static unsigned long target_load(int cpu, int imbalance_pct)
 	/*
 	 * Bias target load with imbalance_pct.
 	 */
-	total = total * imbalance_pct / 100;
-
-	return max(rq->cpu_load, total);
+	return total * imbalance_pct / 100;
 }
 
 static unsigned long power_of(int cpu)
-- 
1.8.1.2

[PATCH 07/10] sched: replace source_load by weighted_cpuload

[Alex Shi]

Now, without load_idx source_load is just weighted_cpuload, so
replace it to reduce a conception for cpu load.

Signed-off-by: Alex Shi <alex.shi@linaro.org>
---
 kernel/sched/fair.c | 21 ++++-----------------
 1 file changed, 4 insertions(+), 17 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d91d925..66fa69b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1015,7 +1015,6 @@ bool should_numa_migrate_memory(struct task_struct *p, struct page * page,
 }
 
 static unsigned long weighted_cpuload(const int cpu);
-static unsigned long source_load(int cpu);
 static unsigned long target_load(int cpu, int imbalance_pct);
 static unsigned long power_of(int cpu);
 static long effective_load(struct task_group *tg, int cpu, long wl, long wg);
@@ -3939,27 +3938,15 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 }
 
 #ifdef CONFIG_SMP
-/* Used instead of source_load when we know the type == 0 */
+/* weighted cpu load with runnable time, 'nice' value on CFS class */
 static unsigned long weighted_cpuload(const int cpu)
 {
 	return cpu_rq(cpu)->cfs.runnable_load_avg;
 }
 
 /*
- * Return a low guess at the load of a migration-source cpu weighted
- * according to the scheduling class and "nice" value.
- *
- * We want to under-estimate the load of migration sources, to
- * balance conservatively.
- */
-static unsigned long source_load(int cpu)
-{
-	return weighted_cpuload(cpu);
-}
-
-/*
  * Return a high guess at the load of a migration-target cpu weighted
- * according to the scheduling class and "nice" value.
+ * according to the runnable time and "nice" value.
  */
 static unsigned long target_load(int cpu, int imbalance_pct)
 {
@@ -4287,7 +4274,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
 		for_each_cpu(i, sched_group_cpus(group)) {
 			/* Bias balancing toward cpus of our domain */
 			if (local_group)
-				load = source_load(i);
+				load = weighted_cpuload(i);
 			else
 				load = target_load(i, imbalance);
 
@@ -5752,7 +5739,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 		if (local_group && env->idle != CPU_IDLE)
 			load = target_load(i, bias);
 		else
-			load = source_load(i);
+			load = weighted_cpuload(i);
 
 		sgs->group_load += load;
 		sgs->sum_nr_running += rq->nr_running;
-- 
1.8.1.2

[PATCH 08/10] sched: remove rq->cpu_load and rq->nr_load_updates

[Alex Shi]

The cpu_load is the copy of rq->cfs.runnable_load_avg. And it updated
on time. So we can use the latter directly. Thus saved 2 rq variables:
cpu_load and nr_load_updates.
Then don't need __update_cpu_load(), just keep sched_avg_update().
Thus removed get_rq_runnable_load() which used for update_cpu_load only.

Signed-off-by: Alex Shi <alex.shi@linaro.org>
---
 kernel/sched/core.c  |  2 --
 kernel/sched/debug.c |  2 --
 kernel/sched/proc.c  | 55 +++++++++++++---------------------------------------
 kernel/sched/sched.h |  2 --
 4 files changed, 13 insertions(+), 48 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index ac2f10c..32602595 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6800,8 +6800,6 @@ void __init sched_init(void)
 		INIT_LIST_HEAD(&rq->leaf_rt_rq_list);
 		init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
 #endif
-
-		rq->cpu_load = 0;
 		rq->last_load_update_tick = jiffies;
 
 #ifdef CONFIG_SMP
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index a24d549..83737ce 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -298,12 +298,10 @@ do {									\
 	SEQ_printf(m, "  .%-30s: %lu\n", "load",
 		   rq->load.weight);
 	P(nr_switches);
-	P(nr_load_updates);
 	P(nr_uninterruptible);
 	PN(next_balance);
 	SEQ_printf(m, "  .%-30s: %ld\n", "curr->pid", (long)(task_pid_nr(rq->curr)));
 	PN(clock);
-	P(cpu_load);
 #undef P
 #undef PN
 
diff --git a/kernel/sched/proc.c b/kernel/sched/proc.c
index 383c4ba..dd3c2d9 100644
--- a/kernel/sched/proc.c
+++ b/kernel/sched/proc.c
@@ -8,12 +8,19 @@
 
 #include "sched.h"
 
+#ifdef CONFIG_SMP
 unsigned long this_cpu_load(void)
 {
-	struct rq *this = this_rq();
-	return this->cpu_load;
+	struct rq *rq = this_rq();
+	return rq->cfs.runnable_load_avg;
 }
-
+#else
+unsigned long this_cpu_load(void)
+{
+	struct rq *rq = this_rq();
+	return rq->load.weight;
+}
+#endif
 
 /*
  * Global load-average calculations
@@ -398,34 +405,6 @@ static void calc_load_account_active(struct rq *this_rq)
  * End of global load-average stuff
  */
 
-
-/*
- * Update rq->cpu_load statistics. This function is usually called every
- * scheduler tick (TICK_NSEC). With tickless idle this will not be called
- * every tick. We fix it up based on jiffies.
- */
-static void __update_cpu_load(struct rq *this_rq, unsigned long this_load)
-{
-	this_rq->nr_load_updates++;
-
-	/* Update our load: */
-	this_rq->cpu_load = this_load; /* Fasttrack for idx 0 */
-
-	sched_avg_update(this_rq);
-}
-
-#ifdef CONFIG_SMP
-static inline unsigned long get_rq_runnable_load(struct rq *rq)
-{
-	return rq->cfs.runnable_load_avg;
-}
-#else
-static inline unsigned long get_rq_runnable_load(struct rq *rq)
-{
-	return rq->load.weight;
-}
-#endif
-
 #ifdef CONFIG_NO_HZ_COMMON
 /*
  * There is no sane way to deal with nohz on smp when using jiffies because the
@@ -447,17 +426,15 @@ static inline unsigned long get_rq_runnable_load(struct rq *rq)
 void update_idle_cpu_load(struct rq *this_rq)
 {
 	unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
-	unsigned long load = get_rq_runnable_load(this_rq);
 
 	/*
 	 * bail if there's load or we're actually up-to-date.
 	 */
-	if (load || curr_jiffies == this_rq->last_load_update_tick)
+	if (curr_jiffies == this_rq->last_load_update_tick)
 		return;
 
 	this_rq->last_load_update_tick = curr_jiffies;
-
-	__update_cpu_load(this_rq, load);
+	sched_avg_update(this_rq);
 }
 
 /*
@@ -466,7 +443,6 @@ void update_idle_cpu_load(struct rq *this_rq)
 void update_cpu_load_nohz(void)
 {
 	struct rq *this_rq = this_rq();
-
 	update_idle_cpu_load(this_rq);
 }
 #endif /* CONFIG_NO_HZ */
@@ -476,12 +452,7 @@ void update_cpu_load_nohz(void)
  */
 void update_cpu_load_active(struct rq *this_rq)
 {
-	unsigned long load = get_rq_runnable_load(this_rq);
-	/*
-	 * See the mess around update_idle_cpu_load() / update_cpu_load_nohz().
-	 */
 	this_rq->last_load_update_tick = jiffies;
-	__update_cpu_load(this_rq, load);
-
+	sched_avg_update(this_rq);
 	calc_load_account_active(this_rq);
 }
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 5b2d4a1..c623131 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -517,7 +517,6 @@ struct rq {
 	unsigned int nr_numa_running;
 	unsigned int nr_preferred_running;
 #endif
-	unsigned long cpu_load;
 	unsigned long last_load_update_tick;
 #ifdef CONFIG_NO_HZ_COMMON
 	u64 nohz_stamp;
@@ -530,7 +529,6 @@ struct rq {
 
 	/* capture load from *all* tasks on this cpu: */
 	struct load_weight load;
-	unsigned long nr_load_updates;
 	u64 nr_switches;
 
 	struct cfs_rq cfs;
-- 
1.8.1.2

[PATCH 09/10] sched: rename update_*_cpu_load

[Alex Shi]

Since we have no cpu_load update, rename the related functions:
s/update_idle_cpu_load/update_idle_rt_avg/
s/update_cpu_load_nohz/update_rt_avg_nohz/
s/update_cpu_load_active/update_avg_load_active/

No functional change.

Signed-off-by: Alex Shi <alex.shi@linaro.org>
---
 include/linux/sched.h    | 2 +-
 kernel/sched/core.c      | 2 +-
 kernel/sched/fair.c      | 2 +-
 kernel/sched/proc.c      | 8 ++++----
 kernel/sched/sched.h     | 4 ++--
 kernel/time/tick-sched.c | 2 +-
 6 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6c416c8..f6afcb3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -174,7 +174,7 @@ extern unsigned long this_cpu_load(void);
 
 
 extern void calc_global_load(unsigned long ticks);
-extern void update_cpu_load_nohz(void);
+extern void update_rt_avg_nohz(void);
 
 extern unsigned long get_parent_ip(unsigned long addr);
 
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 32602595..74dae0e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2431,7 +2431,7 @@ void scheduler_tick(void)
 	raw_spin_lock(&rq->lock);
 	update_rq_clock(rq);
 	curr->sched_class->task_tick(rq, curr, 0);
-	update_cpu_load_active(rq);
+	update_avg_load_active(rq);
 	raw_spin_unlock(&rq->lock);
 
 	perf_event_task_tick();
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 66fa69b..6469c7a 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6986,7 +6986,7 @@ static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
 
 		raw_spin_lock_irq(&rq->lock);
 		update_rq_clock(rq);
-		update_idle_cpu_load(rq);
+		update_idle_rt_avg(rq);
 		raw_spin_unlock_irq(&rq->lock);
 
 		rebalance_domains(rq, CPU_IDLE);
diff --git a/kernel/sched/proc.c b/kernel/sched/proc.c
index dd3c2d9..42b7706 100644
--- a/kernel/sched/proc.c
+++ b/kernel/sched/proc.c
@@ -423,7 +423,7 @@ static void calc_load_account_active(struct rq *this_rq)
  * Called from nohz_idle_balance() to update the load ratings before doing the
  * idle balance.
  */
-void update_idle_cpu_load(struct rq *this_rq)
+void update_idle_rt_avg(struct rq *this_rq)
 {
 	unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
 
@@ -440,17 +440,17 @@ void update_idle_cpu_load(struct rq *this_rq)
 /*
  * Called from tick_nohz_idle_exit()
  */
-void update_cpu_load_nohz(void)
+void update_rt_avg_nohz(void)
 {
 	struct rq *this_rq = this_rq();
-	update_idle_cpu_load(this_rq);
+	update_idle_rt_avg(this_rq);
 }
 #endif /* CONFIG_NO_HZ */
 
 /*
  * Called from scheduler_tick()
  */
-void update_cpu_load_active(struct rq *this_rq)
+void update_avg_load_active(struct rq *this_rq)
 {
 	this_rq->last_load_update_tick = jiffies;
 	sched_avg_update(this_rq);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c623131..ab310c2 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -21,7 +21,7 @@ extern unsigned long calc_load_update;
 extern atomic_long_t calc_load_tasks;
 
 extern long calc_load_fold_active(struct rq *this_rq);
-extern void update_cpu_load_active(struct rq *this_rq);
+extern void update_avg_load_active(struct rq *this_rq);
 
 /*
  * Helpers for converting nanosecond timing to jiffy resolution
@@ -1194,7 +1194,7 @@ extern void init_dl_task_timer(struct sched_dl_entity *dl_se);
 
 unsigned long to_ratio(u64 period, u64 runtime);
 
-extern void update_idle_cpu_load(struct rq *this_rq);
+extern void update_idle_rt_avg(struct rq *this_rq);
 
 extern void init_task_runnable_average(struct task_struct *p);
 
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 9f8af69..b1a400a 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -866,7 +866,7 @@ static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now)
 {
 	/* Update jiffies first */
 	tick_do_update_jiffies64(now);
-	update_cpu_load_nohz();
+	update_rt_avg_nohz();
 
 	calc_load_exit_idle();
 	touch_softlockup_watchdog();
-- 
1.8.1.2

[PATCH 10/10] sched: clean up task_hot function

[Alex Shi]

task_hot doesn't need the 'sched_domain' parameter, so remove it.

Signed-off-by: Alex Shi <alex.shi@linaro.org>
---
 kernel/sched/fair.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6469c7a..b0c189d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5003,7 +5003,7 @@ static void move_task(struct task_struct *p, struct lb_env *env)
  * Is this task likely cache-hot:
  */
 static int
-task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
+task_hot(struct task_struct *p, u64 now)
 {
 	s64 delta;
 
@@ -5164,7 +5164,7 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
 	 * 2) task is cache cold, or
 	 * 3) too many balance attempts have failed.
 	 */
-	tsk_cache_hot = task_hot(p, rq_clock_task(env->src_rq), env->sd);
+	tsk_cache_hot = task_hot(p, rq_clock_task(env->src_rq));
 	if (!tsk_cache_hot)
 		tsk_cache_hot = migrate_degrades_locality(p, env);
 
-- 
1.8.1.2