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Date: Tue, 3 Sep 2013 15:57:35 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Thomas Gleixner <tglx@...utronix.de>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: [GIT PULL] scheduler changes for v3.12
Linus,
Please pull the latest sched-core-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-core-for-linus
HEAD: 10866e62e8a6907d9072f10f9a0561db0c0cf50b sched/fair: Fix the sd_parent_degenerate() code
Various optimizations, cleanups and smaller fixes - no major changes in
scheduler behavior.
Thanks,
Ingo
------------------>
Christoph Lameter (1):
sched/cputime: Use this_cpu_add() in task_group_account_field()
Joonsoo Kim (3):
sched: Remove one division operation in find_busiest_queue()
sched: Factor out code to should_we_balance()
sched: Clean-up struct sd_lb_stat
Kirill Tkhai (2):
sched/__wake_up_sync_key(): Fix nr_exclusive tasks which lead to WF_SYNC clearing
sched/fair: Cleanup: remove duplicate variable declaration
Peter Zijlstra (6):
sched/fair: Shrink sg_lb_stats and play memset games
sched/fair: Remove duplicate load_per_task computations
sched/fair: Make group power more consistent
sched/fair: Optimize find_busiest_queue()
sched/fair: Rework and comment the group_imb code
sched/fair: Fix the sd_parent_degenerate() code
Rik van Riel (1):
sched/x86: Optimize switch_mm() for multi-threaded workloads
Tom Rini (1):
numa: Mark __node_set() as __always_inline
Xiaotian Feng (1):
cpumask: Fix cpumask leak in partition_sched_domains()
Xie XiuQi (1):
generic-ipi: Kill unnecessary variable - csd_flags
arch/x86/include/asm/mmu_context.h | 20 +-
include/linux/nodemask.h | 11 +-
kernel/sched/core.c | 17 +-
kernel/sched/cputime.c | 2 +-
kernel/sched/fair.c | 511 +++++++++++++++++++++----------------
kernel/smp.c | 14 +-
6 files changed, 326 insertions(+), 249 deletions(-)
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index cdbf367..be12c53 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -45,22 +45,28 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
/* Re-load page tables */
load_cr3(next->pgd);
- /* stop flush ipis for the previous mm */
+ /* Stop flush ipis for the previous mm */
cpumask_clear_cpu(cpu, mm_cpumask(prev));
- /*
- * load the LDT, if the LDT is different:
- */
+ /* Load the LDT, if the LDT is different: */
if (unlikely(prev->context.ldt != next->context.ldt))
load_LDT_nolock(&next->context);
}
#ifdef CONFIG_SMP
- else {
+ else {
this_cpu_write(cpu_tlbstate.state, TLBSTATE_OK);
BUG_ON(this_cpu_read(cpu_tlbstate.active_mm) != next);
- if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next))) {
- /* We were in lazy tlb mode and leave_mm disabled
+ if (!cpumask_test_cpu(cpu, mm_cpumask(next))) {
+ /*
+ * On established mms, the mm_cpumask is only changed
+ * from irq context, from ptep_clear_flush() while in
+ * lazy tlb mode, and here. Irqs are blocked during
+ * schedule, protecting us from simultaneous changes.
+ */
+ cpumask_set_cpu(cpu, mm_cpumask(next));
+ /*
+ * We were in lazy tlb mode and leave_mm disabled
* tlb flush IPI delivery. We must reload CR3
* to make sure to use no freed page tables.
*/
diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h
index 4e2cbfa..58b9a02 100644
--- a/include/linux/nodemask.h
+++ b/include/linux/nodemask.h
@@ -98,8 +98,17 @@
typedef struct { DECLARE_BITMAP(bits, MAX_NUMNODES); } nodemask_t;
extern nodemask_t _unused_nodemask_arg_;
+/*
+ * The inline keyword gives the compiler room to decide to inline, or
+ * not inline a function as it sees best. However, as these functions
+ * are called in both __init and non-__init functions, if they are not
+ * inlined we will end up with a section mis-match error (of the type of
+ * freeable items not being freed). So we must use __always_inline here
+ * to fix the problem. If other functions in the future also end up in
+ * this situation they will also need to be annotated as __always_inline
+ */
#define node_set(node, dst) __node_set((node), &(dst))
-static inline void __node_set(int node, volatile nodemask_t *dstp)
+static __always_inline void __node_set(int node, volatile nodemask_t *dstp)
{
set_bit(node, dstp->bits);
}
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b7c32cb..4da0f4b 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2660,7 +2660,7 @@ void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode,
if (unlikely(!q))
return;
- if (unlikely(!nr_exclusive))
+ if (unlikely(nr_exclusive != 1))
wake_flags = 0;
spin_lock_irqsave(&q->lock, flags);
@@ -4914,7 +4914,8 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
SD_BALANCE_FORK |
SD_BALANCE_EXEC |
SD_SHARE_CPUPOWER |
- SD_SHARE_PKG_RESOURCES);
+ SD_SHARE_PKG_RESOURCES |
+ SD_PREFER_SIBLING);
if (nr_node_ids == 1)
pflags &= ~SD_SERIALIZE;
}
@@ -5118,6 +5119,13 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
tmp->parent = parent->parent;
if (parent->parent)
parent->parent->child = tmp;
+ /*
+ * Transfer SD_PREFER_SIBLING down in case of a
+ * degenerate parent; the spans match for this
+ * so the property transfers.
+ */
+ if (parent->flags & SD_PREFER_SIBLING)
+ tmp->flags |= SD_PREFER_SIBLING;
destroy_sched_domain(parent, cpu);
} else
tmp = tmp->parent;
@@ -6184,8 +6192,9 @@ match1:
;
}
+ n = ndoms_cur;
if (doms_new == NULL) {
- ndoms_cur = 0;
+ n = 0;
doms_new = &fallback_doms;
cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
WARN_ON_ONCE(dattr_new);
@@ -6193,7 +6202,7 @@ match1:
/* Build new domains */
for (i = 0; i < ndoms_new; i++) {
- for (j = 0; j < ndoms_cur && !new_topology; j++) {
+ for (j = 0; j < n && !new_topology; j++) {
if (cpumask_equal(doms_new[i], doms_cur[j])
&& dattrs_equal(dattr_new, i, dattr_cur, j))
goto match2;
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index a7959e0..e89ccef 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -121,7 +121,7 @@ static inline void task_group_account_field(struct task_struct *p, int index,
* is the only cgroup, then nothing else should be necessary.
*
*/
- __get_cpu_var(kernel_cpustat).cpustat[index] += tmp;
+ __this_cpu_add(kernel_cpustat.cpustat[index], tmp);
cpuacct_account_field(p, index, tmp);
}
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 9565645..dffb270 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4232,50 +4232,56 @@ static unsigned long task_h_load(struct task_struct *p)
/********** Helpers for find_busiest_group ************************/
/*
- * sd_lb_stats - Structure to store the statistics of a sched_domain
- * during load balancing.
- */
-struct sd_lb_stats {
- struct sched_group *busiest; /* Busiest group in this sd */
- struct sched_group *this; /* Local group in this sd */
- unsigned long total_load; /* Total load of all groups in sd */
- unsigned long total_pwr; /* Total power of all groups in sd */
- unsigned long avg_load; /* Average load across all groups in sd */
-
- /** Statistics of this group */
- unsigned long this_load;
- unsigned long this_load_per_task;
- unsigned long this_nr_running;
- unsigned long this_has_capacity;
- unsigned int this_idle_cpus;
-
- /* Statistics of the busiest group */
- unsigned int busiest_idle_cpus;
- unsigned long max_load;
- unsigned long busiest_load_per_task;
- unsigned long busiest_nr_running;
- unsigned long busiest_group_capacity;
- unsigned long busiest_has_capacity;
- unsigned int busiest_group_weight;
-
- int group_imb; /* Is there imbalance in this sd */
-};
-
-/*
* sg_lb_stats - stats of a sched_group required for load_balancing
*/
struct sg_lb_stats {
unsigned long avg_load; /*Avg load across the CPUs of the group */
unsigned long group_load; /* Total load over the CPUs of the group */
- unsigned long sum_nr_running; /* Nr tasks running in the group */
unsigned long sum_weighted_load; /* Weighted load of group's tasks */
- unsigned long group_capacity;
- unsigned long idle_cpus;
- unsigned long group_weight;
+ unsigned long load_per_task;
+ unsigned long group_power;
+ unsigned int sum_nr_running; /* Nr tasks running in the group */
+ unsigned int group_capacity;
+ unsigned int idle_cpus;
+ unsigned int group_weight;
int group_imb; /* Is there an imbalance in the group ? */
int group_has_capacity; /* Is there extra capacity in the group? */
};
+/*
+ * sd_lb_stats - Structure to store the statistics of a sched_domain
+ * during load balancing.
+ */
+struct sd_lb_stats {
+ struct sched_group *busiest; /* Busiest group in this sd */
+ struct sched_group *local; /* Local group in this sd */
+ unsigned long total_load; /* Total load of all groups in sd */
+ unsigned long total_pwr; /* Total power of all groups in sd */
+ unsigned long avg_load; /* Average load across all groups in sd */
+
+ struct sg_lb_stats busiest_stat;/* Statistics of the busiest group */
+ struct sg_lb_stats local_stat; /* Statistics of the local group */
+};
+
+static inline void init_sd_lb_stats(struct sd_lb_stats *sds)
+{
+ /*
+ * Skimp on the clearing to avoid duplicate work. We can avoid clearing
+ * local_stat because update_sg_lb_stats() does a full clear/assignment.
+ * We must however clear busiest_stat::avg_load because
+ * update_sd_pick_busiest() reads this before assignment.
+ */
+ *sds = (struct sd_lb_stats){
+ .busiest = NULL,
+ .local = NULL,
+ .total_load = 0UL,
+ .total_pwr = 0UL,
+ .busiest_stat = {
+ .avg_load = 0UL,
+ },
+ };
+}
+
/**
* get_sd_load_idx - Obtain the load index for a given sched domain.
* @sd: The sched_domain whose load_idx is to be obtained.
@@ -4457,33 +4463,99 @@ fix_small_capacity(struct sched_domain *sd, struct sched_group *group)
return 0;
}
+/*
+ * Group imbalance indicates (and tries to solve) the problem where balancing
+ * groups is inadequate due to tsk_cpus_allowed() constraints.
+ *
+ * Imagine a situation of two groups of 4 cpus each and 4 tasks each with a
+ * cpumask covering 1 cpu of the first group and 3 cpus of the second group.
+ * Something like:
+ *
+ * { 0 1 2 3 } { 4 5 6 7 }
+ * * * * *
+ *
+ * If we were to balance group-wise we'd place two tasks in the first group and
+ * two tasks in the second group. Clearly this is undesired as it will overload
+ * cpu 3 and leave one of the cpus in the second group unused.
+ *
+ * The current solution to this issue is detecting the skew in the first group
+ * by noticing it has a cpu that is overloaded while the remaining cpus are
+ * idle -- or rather, there's a distinct imbalance in the cpus; see
+ * sg_imbalanced().
+ *
+ * When this is so detected; this group becomes a candidate for busiest; see
+ * update_sd_pick_busiest(). And calculcate_imbalance() and
+ * find_busiest_group() avoid some of the usual balance conditional to allow it
+ * to create an effective group imbalance.
+ *
+ * This is a somewhat tricky proposition since the next run might not find the
+ * group imbalance and decide the groups need to be balanced again. A most
+ * subtle and fragile situation.
+ */
+
+struct sg_imb_stats {
+ unsigned long max_nr_running, min_nr_running;
+ unsigned long max_cpu_load, min_cpu_load;
+};
+
+static inline void init_sg_imb_stats(struct sg_imb_stats *sgi)
+{
+ sgi->max_cpu_load = sgi->max_nr_running = 0UL;
+ sgi->min_cpu_load = sgi->min_nr_running = ~0UL;
+}
+
+static inline void
+update_sg_imb_stats(struct sg_imb_stats *sgi,
+ unsigned long load, unsigned long nr_running)
+{
+ if (load > sgi->max_cpu_load)
+ sgi->max_cpu_load = load;
+ if (sgi->min_cpu_load > load)
+ sgi->min_cpu_load = load;
+
+ if (nr_running > sgi->max_nr_running)
+ sgi->max_nr_running = nr_running;
+ if (sgi->min_nr_running > nr_running)
+ sgi->min_nr_running = nr_running;
+}
+
+static inline int
+sg_imbalanced(struct sg_lb_stats *sgs, struct sg_imb_stats *sgi)
+{
+ /*
+ * Consider the group unbalanced when the imbalance is larger
+ * than the average weight of a task.
+ *
+ * APZ: with cgroup the avg task weight can vary wildly and
+ * might not be a suitable number - should we keep a
+ * normalized nr_running number somewhere that negates
+ * the hierarchy?
+ */
+ if ((sgi->max_cpu_load - sgi->min_cpu_load) >= sgs->load_per_task &&
+ (sgi->max_nr_running - sgi->min_nr_running) > 1)
+ return 1;
+
+ return 0;
+}
+
/**
* 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.
- * @balance: Should we balance.
* @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,
- int local_group, int *balance, struct sg_lb_stats *sgs)
+ int local_group, struct sg_lb_stats *sgs)
{
- unsigned long nr_running, max_nr_running, min_nr_running;
- unsigned long load, max_cpu_load, min_cpu_load;
- unsigned int balance_cpu = -1, first_idle_cpu = 0;
- unsigned long avg_load_per_task = 0;
+ struct sg_imb_stats sgi;
+ unsigned long nr_running;
+ unsigned long load;
int i;
- if (local_group)
- balance_cpu = group_balance_cpu(group);
-
- /* Tally up the load of all CPUs in the group */
- max_cpu_load = 0;
- min_cpu_load = ~0UL;
- max_nr_running = 0;
- min_nr_running = ~0UL;
+ init_sg_imb_stats(&sgi);
for_each_cpu_and(i, sched_group_cpus(group), env->cpus) {
struct rq *rq = cpu_rq(i);
@@ -4492,24 +4564,10 @@ static inline void update_sg_lb_stats(struct lb_env *env,
/* Bias balancing toward cpus of our domain */
if (local_group) {
- if (idle_cpu(i) && !first_idle_cpu &&
- cpumask_test_cpu(i, sched_group_mask(group))) {
- first_idle_cpu = 1;
- balance_cpu = i;
- }
-
load = target_load(i, load_idx);
} else {
load = source_load(i, load_idx);
- if (load > max_cpu_load)
- max_cpu_load = load;
- if (min_cpu_load > load)
- min_cpu_load = load;
-
- if (nr_running > max_nr_running)
- max_nr_running = nr_running;
- if (min_nr_running > nr_running)
- min_nr_running = nr_running;
+ update_sg_imb_stats(&sgi, load, nr_running);
}
sgs->group_load += load;
@@ -4519,46 +4577,25 @@ static inline void update_sg_lb_stats(struct lb_env *env,
sgs->idle_cpus++;
}
- /*
- * First idle cpu or the first cpu(busiest) in this sched group
- * is eligible for doing load balancing at this and above
- * domains. In the newly idle case, we will allow all the cpu's
- * to do the newly idle load balance.
- */
- if (local_group) {
- if (env->idle != CPU_NEWLY_IDLE) {
- if (balance_cpu != env->dst_cpu) {
- *balance = 0;
- return;
- }
- update_group_power(env->sd, env->dst_cpu);
- } else if (time_after_eq(jiffies, group->sgp->next_update))
- update_group_power(env->sd, env->dst_cpu);
- }
+ if (local_group && (env->idle != CPU_NEWLY_IDLE ||
+ time_after_eq(jiffies, group->sgp->next_update)))
+ update_group_power(env->sd, env->dst_cpu);
/* Adjust by relative CPU power of the group */
- sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->sgp->power;
+ sgs->group_power = group->sgp->power;
+ sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / sgs->group_power;
- /*
- * Consider the group unbalanced when the imbalance is larger
- * than the average weight of a task.
- *
- * APZ: with cgroup the avg task weight can vary wildly and
- * might not be a suitable number - should we keep a
- * normalized nr_running number somewhere that negates
- * the hierarchy?
- */
if (sgs->sum_nr_running)
- avg_load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;
+ sgs->load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;
- if ((max_cpu_load - min_cpu_load) >= avg_load_per_task &&
- (max_nr_running - min_nr_running) > 1)
- sgs->group_imb = 1;
+ sgs->group_imb = sg_imbalanced(sgs, &sgi);
+
+ sgs->group_capacity =
+ DIV_ROUND_CLOSEST(sgs->group_power, SCHED_POWER_SCALE);
- sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power,
- SCHED_POWER_SCALE);
if (!sgs->group_capacity)
sgs->group_capacity = fix_small_capacity(env->sd, group);
+
sgs->group_weight = group->group_weight;
if (sgs->group_capacity > sgs->sum_nr_running)
@@ -4580,7 +4617,7 @@ static bool update_sd_pick_busiest(struct lb_env *env,
struct sched_group *sg,
struct sg_lb_stats *sgs)
{
- if (sgs->avg_load <= sds->max_load)
+ if (sgs->avg_load <= sds->busiest_stat.avg_load)
return false;
if (sgs->sum_nr_running > sgs->group_capacity)
@@ -4613,11 +4650,11 @@ static bool update_sd_pick_busiest(struct lb_env *env,
* @sds: variable to hold the statistics for this sched_domain.
*/
static inline void update_sd_lb_stats(struct lb_env *env,
- int *balance, struct sd_lb_stats *sds)
+ struct sd_lb_stats *sds)
{
struct sched_domain *child = env->sd->child;
struct sched_group *sg = env->sd->groups;
- struct sg_lb_stats sgs;
+ struct sg_lb_stats tmp_sgs;
int load_idx, prefer_sibling = 0;
if (child && child->flags & SD_PREFER_SIBLING)
@@ -4626,17 +4663,17 @@ static inline void update_sd_lb_stats(struct lb_env *env,
load_idx = get_sd_load_idx(env->sd, env->idle);
do {
+ struct sg_lb_stats *sgs = &tmp_sgs;
int local_group;
local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg));
- memset(&sgs, 0, sizeof(sgs));
- update_sg_lb_stats(env, sg, load_idx, local_group, balance, &sgs);
-
- if (local_group && !(*balance))
- return;
+ if (local_group) {
+ sds->local = sg;
+ sgs = &sds->local_stat;
+ }
- sds->total_load += sgs.group_load;
- sds->total_pwr += sg->sgp->power;
+ memset(sgs, 0, sizeof(*sgs));
+ update_sg_lb_stats(env, sg, load_idx, local_group, sgs);
/*
* In case the child domain prefers tasks go to siblings
@@ -4648,26 +4685,17 @@ static inline void update_sd_lb_stats(struct lb_env *env,
* heaviest group when it is already under-utilized (possible
* with a large weight task outweighs the tasks on the system).
*/
- if (prefer_sibling && !local_group && sds->this_has_capacity)
- sgs.group_capacity = min(sgs.group_capacity, 1UL);
+ if (prefer_sibling && !local_group &&
+ sds->local && sds->local_stat.group_has_capacity)
+ sgs->group_capacity = min(sgs->group_capacity, 1U);
- if (local_group) {
- sds->this_load = sgs.avg_load;
- sds->this = sg;
- sds->this_nr_running = sgs.sum_nr_running;
- sds->this_load_per_task = sgs.sum_weighted_load;
- sds->this_has_capacity = sgs.group_has_capacity;
- sds->this_idle_cpus = sgs.idle_cpus;
- } else if (update_sd_pick_busiest(env, sds, sg, &sgs)) {
- sds->max_load = sgs.avg_load;
+ /* Now, start updating sd_lb_stats */
+ sds->total_load += sgs->group_load;
+ sds->total_pwr += sgs->group_power;
+
+ if (!local_group && update_sd_pick_busiest(env, sds, sg, sgs)) {
sds->busiest = sg;
- sds->busiest_nr_running = sgs.sum_nr_running;
- sds->busiest_idle_cpus = sgs.idle_cpus;
- sds->busiest_group_capacity = sgs.group_capacity;
- sds->busiest_load_per_task = sgs.sum_weighted_load;
- sds->busiest_has_capacity = sgs.group_has_capacity;
- sds->busiest_group_weight = sgs.group_weight;
- sds->group_imb = sgs.group_imb;
+ sds->busiest_stat = *sgs;
}
sg = sg->next;
@@ -4712,7 +4740,8 @@ static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds)
return 0;
env->imbalance = DIV_ROUND_CLOSEST(
- sds->max_load * sds->busiest->sgp->power, SCHED_POWER_SCALE);
+ sds->busiest_stat.avg_load * sds->busiest_stat.group_power,
+ SCHED_POWER_SCALE);
return 1;
}
@@ -4730,24 +4759,23 @@ void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
unsigned long tmp, pwr_now = 0, pwr_move = 0;
unsigned int imbn = 2;
unsigned long scaled_busy_load_per_task;
+ struct sg_lb_stats *local, *busiest;
- if (sds->this_nr_running) {
- sds->this_load_per_task /= sds->this_nr_running;
- if (sds->busiest_load_per_task >
- sds->this_load_per_task)
- imbn = 1;
- } else {
- sds->this_load_per_task =
- cpu_avg_load_per_task(env->dst_cpu);
- }
+ local = &sds->local_stat;
+ busiest = &sds->busiest_stat;
- scaled_busy_load_per_task = sds->busiest_load_per_task
- * SCHED_POWER_SCALE;
- scaled_busy_load_per_task /= sds->busiest->sgp->power;
+ if (!local->sum_nr_running)
+ local->load_per_task = cpu_avg_load_per_task(env->dst_cpu);
+ else if (busiest->load_per_task > local->load_per_task)
+ imbn = 1;
- if (sds->max_load - sds->this_load + scaled_busy_load_per_task >=
- (scaled_busy_load_per_task * imbn)) {
- env->imbalance = sds->busiest_load_per_task;
+ scaled_busy_load_per_task =
+ (busiest->load_per_task * SCHED_POWER_SCALE) /
+ busiest->group_power;
+
+ if (busiest->avg_load - local->avg_load + scaled_busy_load_per_task >=
+ (scaled_busy_load_per_task * imbn)) {
+ env->imbalance = busiest->load_per_task;
return;
}
@@ -4757,34 +4785,37 @@ void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
* moving them.
*/
- pwr_now += sds->busiest->sgp->power *
- min(sds->busiest_load_per_task, sds->max_load);
- pwr_now += sds->this->sgp->power *
- min(sds->this_load_per_task, sds->this_load);
+ pwr_now += busiest->group_power *
+ min(busiest->load_per_task, busiest->avg_load);
+ pwr_now += local->group_power *
+ min(local->load_per_task, local->avg_load);
pwr_now /= SCHED_POWER_SCALE;
/* Amount of load we'd subtract */
- tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
- sds->busiest->sgp->power;
- if (sds->max_load > tmp)
- pwr_move += sds->busiest->sgp->power *
- min(sds->busiest_load_per_task, sds->max_load - tmp);
+ tmp = (busiest->load_per_task * SCHED_POWER_SCALE) /
+ busiest->group_power;
+ if (busiest->avg_load > tmp) {
+ pwr_move += busiest->group_power *
+ min(busiest->load_per_task,
+ busiest->avg_load - tmp);
+ }
/* Amount of load we'd add */
- if (sds->max_load * sds->busiest->sgp->power <
- sds->busiest_load_per_task * SCHED_POWER_SCALE)
- tmp = (sds->max_load * sds->busiest->sgp->power) /
- sds->this->sgp->power;
- else
- tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
- sds->this->sgp->power;
- pwr_move += sds->this->sgp->power *
- min(sds->this_load_per_task, sds->this_load + tmp);
+ if (busiest->avg_load * busiest->group_power <
+ busiest->load_per_task * SCHED_POWER_SCALE) {
+ tmp = (busiest->avg_load * busiest->group_power) /
+ local->group_power;
+ } else {
+ tmp = (busiest->load_per_task * SCHED_POWER_SCALE) /
+ local->group_power;
+ }
+ pwr_move += local->group_power *
+ min(local->load_per_task, local->avg_load + tmp);
pwr_move /= SCHED_POWER_SCALE;
/* Move if we gain throughput */
if (pwr_move > pwr_now)
- env->imbalance = sds->busiest_load_per_task;
+ env->imbalance = busiest->load_per_task;
}
/**
@@ -4796,11 +4827,18 @@ void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
{
unsigned long max_pull, load_above_capacity = ~0UL;
+ struct sg_lb_stats *local, *busiest;
+
+ local = &sds->local_stat;
+ busiest = &sds->busiest_stat;
- sds->busiest_load_per_task /= sds->busiest_nr_running;
- if (sds->group_imb) {
- sds->busiest_load_per_task =
- min(sds->busiest_load_per_task, sds->avg_load);
+ if (busiest->group_imb) {
+ /*
+ * In the group_imb case we cannot rely on group-wide averages
+ * to ensure cpu-load equilibrium, look at wider averages. XXX
+ */
+ busiest->load_per_task =
+ min(busiest->load_per_task, sds->avg_load);
}
/*
@@ -4808,21 +4846,22 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
* max load less than avg load(as we skip the groups at or below
* its cpu_power, while calculating max_load..)
*/
- if (sds->max_load < sds->avg_load) {
+ if (busiest->avg_load < sds->avg_load) {
env->imbalance = 0;
return fix_small_imbalance(env, sds);
}
- if (!sds->group_imb) {
+ if (!busiest->group_imb) {
/*
* Don't want to pull so many tasks that a group would go idle.
+ * Except of course for the group_imb case, since then we might
+ * have to drop below capacity to reach cpu-load equilibrium.
*/
- load_above_capacity = (sds->busiest_nr_running -
- sds->busiest_group_capacity);
+ load_above_capacity =
+ (busiest->sum_nr_running - busiest->group_capacity);
load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE);
-
- load_above_capacity /= sds->busiest->sgp->power;
+ load_above_capacity /= busiest->group_power;
}
/*
@@ -4832,15 +4871,14 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
* we also don't want to reduce the group load below the group capacity
* (so that we can implement power-savings policies etc). Thus we look
* for the minimum possible imbalance.
- * Be careful of negative numbers as they'll appear as very large values
- * with unsigned longs.
*/
- max_pull = min(sds->max_load - sds->avg_load, load_above_capacity);
+ max_pull = min(busiest->avg_load - sds->avg_load, load_above_capacity);
/* How much load to actually move to equalise the imbalance */
- env->imbalance = min(max_pull * sds->busiest->sgp->power,
- (sds->avg_load - sds->this_load) * sds->this->sgp->power)
- / SCHED_POWER_SCALE;
+ env->imbalance = min(
+ max_pull * busiest->group_power,
+ (sds->avg_load - local->avg_load) * local->group_power
+ ) / SCHED_POWER_SCALE;
/*
* if *imbalance is less than the average load per runnable task
@@ -4848,9 +4886,8 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
* a think about bumping its value to force at least one task to be
* moved
*/
- if (env->imbalance < sds->busiest_load_per_task)
+ if (env->imbalance < busiest->load_per_task)
return fix_small_imbalance(env, sds);
-
}
/******* find_busiest_group() helpers end here *********************/
@@ -4866,69 +4903,62 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
* to restore balance.
*
* @env: The load balancing environment.
- * @balance: Pointer to a variable indicating if this_cpu
- * is the appropriate cpu to perform load balancing at this_level.
*
* Returns: - the busiest group if imbalance exists.
* - If no imbalance and user has opted for power-savings balance,
* return the least loaded group whose CPUs can be
* put to idle by rebalancing its tasks onto our group.
*/
-static struct sched_group *
-find_busiest_group(struct lb_env *env, int *balance)
+static struct sched_group *find_busiest_group(struct lb_env *env)
{
+ struct sg_lb_stats *local, *busiest;
struct sd_lb_stats sds;
- memset(&sds, 0, sizeof(sds));
+ init_sd_lb_stats(&sds);
/*
* Compute the various statistics relavent for load balancing at
* this level.
*/
- update_sd_lb_stats(env, balance, &sds);
-
- /*
- * this_cpu is not the appropriate cpu to perform load balancing at
- * this level.
- */
- if (!(*balance))
- goto ret;
+ update_sd_lb_stats(env, &sds);
+ local = &sds.local_stat;
+ busiest = &sds.busiest_stat;
if ((env->idle == CPU_IDLE || env->idle == CPU_NEWLY_IDLE) &&
check_asym_packing(env, &sds))
return sds.busiest;
/* There is no busy sibling group to pull tasks from */
- if (!sds.busiest || sds.busiest_nr_running == 0)
+ if (!sds.busiest || busiest->sum_nr_running == 0)
goto out_balanced;
sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr;
/*
* If the busiest group is imbalanced the below checks don't
- * work because they assumes all things are equal, which typically
+ * work because they assume all things are equal, which typically
* isn't true due to cpus_allowed constraints and the like.
*/
- if (sds.group_imb)
+ if (busiest->group_imb)
goto force_balance;
/* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
- if (env->idle == CPU_NEWLY_IDLE && sds.this_has_capacity &&
- !sds.busiest_has_capacity)
+ if (env->idle == CPU_NEWLY_IDLE && local->group_has_capacity &&
+ !busiest->group_has_capacity)
goto force_balance;
/*
* If the local group is more busy than the selected busiest group
* don't try and pull any tasks.
*/
- if (sds.this_load >= sds.max_load)
+ if (local->avg_load >= busiest->avg_load)
goto out_balanced;
/*
* Don't pull any tasks if this group is already above the domain
* average load.
*/
- if (sds.this_load >= sds.avg_load)
+ if (local->avg_load >= sds.avg_load)
goto out_balanced;
if (env->idle == CPU_IDLE) {
@@ -4938,15 +4968,16 @@ find_busiest_group(struct lb_env *env, int *balance)
* there is no imbalance between this and busiest group
* wrt to idle cpu's, it is balanced.
*/
- if ((sds.this_idle_cpus <= sds.busiest_idle_cpus + 1) &&
- sds.busiest_nr_running <= sds.busiest_group_weight)
+ 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 * sds.max_load <= env->sd->imbalance_pct * sds.this_load)
+ if (100 * busiest->avg_load <=
+ env->sd->imbalance_pct * local->avg_load)
goto out_balanced;
}
@@ -4956,7 +4987,6 @@ force_balance:
return sds.busiest;
out_balanced:
-ret:
env->imbalance = 0;
return NULL;
}
@@ -4968,10 +4998,10 @@ static struct rq *find_busiest_queue(struct lb_env *env,
struct sched_group *group)
{
struct rq *busiest = NULL, *rq;
- unsigned long max_load = 0;
+ unsigned long busiest_load = 0, busiest_power = 1;
int i;
- for_each_cpu(i, sched_group_cpus(group)) {
+ for_each_cpu_and(i, sched_group_cpus(group), env->cpus) {
unsigned long power = power_of(i);
unsigned long capacity = DIV_ROUND_CLOSEST(power,
SCHED_POWER_SCALE);
@@ -4980,9 +5010,6 @@ static struct rq *find_busiest_queue(struct lb_env *env,
if (!capacity)
capacity = fix_small_capacity(env->sd, group);
- if (!cpumask_test_cpu(i, env->cpus))
- continue;
-
rq = cpu_rq(i);
wl = weighted_cpuload(i);
@@ -4998,11 +5025,15 @@ static struct rq *find_busiest_queue(struct lb_env *env,
* the weighted_cpuload() scaled with the cpu power, so that
* the load can be moved away from the cpu that is potentially
* running at a lower capacity.
+ *
+ * Thus we're looking for max(wl_i / power_i), crosswise
+ * multiplication to rid ourselves of the division works out
+ * to: wl_i * power_j > wl_j * power_i; where j is our
+ * previous maximum.
*/
- wl = (wl * SCHED_POWER_SCALE) / power;
-
- if (wl > max_load) {
- max_load = wl;
+ if (wl * busiest_power > busiest_load * power) {
+ busiest_load = wl;
+ busiest_power = power;
busiest = rq;
}
}
@@ -5039,13 +5070,47 @@ static int need_active_balance(struct lb_env *env)
static int active_load_balance_cpu_stop(void *data);
+static int should_we_balance(struct lb_env *env)
+{
+ struct sched_group *sg = env->sd->groups;
+ struct cpumask *sg_cpus, *sg_mask;
+ int cpu, balance_cpu = -1;
+
+ /*
+ * In the newly idle case, we will allow all the cpu's
+ * to do the newly idle load balance.
+ */
+ if (env->idle == CPU_NEWLY_IDLE)
+ return 1;
+
+ sg_cpus = sched_group_cpus(sg);
+ sg_mask = sched_group_mask(sg);
+ /* Try to find first idle cpu */
+ for_each_cpu_and(cpu, sg_cpus, env->cpus) {
+ if (!cpumask_test_cpu(cpu, sg_mask) || !idle_cpu(cpu))
+ continue;
+
+ balance_cpu = cpu;
+ break;
+ }
+
+ if (balance_cpu == -1)
+ balance_cpu = group_balance_cpu(sg);
+
+ /*
+ * First idle cpu or the first cpu(busiest) in this sched group
+ * is eligible for doing load balancing at this and above domains.
+ */
+ return balance_cpu != env->dst_cpu;
+}
+
/*
* Check this_cpu to ensure it is balanced within domain. Attempt to move
* tasks if there is an imbalance.
*/
static int load_balance(int this_cpu, struct rq *this_rq,
struct sched_domain *sd, enum cpu_idle_type idle,
- int *balance)
+ int *continue_balancing)
{
int ld_moved, cur_ld_moved, active_balance = 0;
struct sched_group *group;
@@ -5075,11 +5140,12 @@ static int load_balance(int this_cpu, struct rq *this_rq,
schedstat_inc(sd, lb_count[idle]);
redo:
- group = find_busiest_group(&env, balance);
-
- if (*balance == 0)
+ if (!should_we_balance(&env)) {
+ *continue_balancing = 0;
goto out_balanced;
+ }
+ group = find_busiest_group(&env);
if (!group) {
schedstat_inc(sd, lb_nobusyg[idle]);
goto out_balanced;
@@ -5292,7 +5358,7 @@ void idle_balance(int this_cpu, struct rq *this_rq)
rcu_read_lock();
for_each_domain(this_cpu, sd) {
unsigned long interval;
- int balance = 1;
+ int continue_balancing = 1;
if (!(sd->flags & SD_LOAD_BALANCE))
continue;
@@ -5300,7 +5366,8 @@ void idle_balance(int this_cpu, struct rq *this_rq)
if (sd->flags & SD_BALANCE_NEWIDLE) {
/* If we've pulled tasks over stop searching: */
pulled_task = load_balance(this_cpu, this_rq,
- sd, CPU_NEWLY_IDLE, &balance);
+ sd, CPU_NEWLY_IDLE,
+ &continue_balancing);
}
interval = msecs_to_jiffies(sd->balance_interval);
@@ -5538,7 +5605,7 @@ void update_max_interval(void)
*/
static void rebalance_domains(int cpu, enum cpu_idle_type idle)
{
- int balance = 1;
+ int continue_balancing = 1;
struct rq *rq = cpu_rq(cpu);
unsigned long interval;
struct sched_domain *sd;
@@ -5570,7 +5637,7 @@ static void rebalance_domains(int cpu, enum cpu_idle_type idle)
}
if (time_after_eq(jiffies, sd->last_balance + interval)) {
- if (load_balance(cpu, rq, sd, idle, &balance)) {
+ if (load_balance(cpu, rq, sd, idle, &continue_balancing)) {
/*
* The LBF_SOME_PINNED logic could have changed
* env->dst_cpu, so we can't know our idle
@@ -5593,7 +5660,7 @@ out:
* CPU in our sched group which is doing load balancing more
* actively.
*/
- if (!balance)
+ if (!continue_balancing)
break;
}
rcu_read_unlock();
@@ -5889,11 +5956,9 @@ static void switched_from_fair(struct rq *rq, struct task_struct *p)
* and ensure we don't carry in an old decay_count if we
* switch back.
*/
- if (p->se.avg.decay_count) {
- struct cfs_rq *cfs_rq = cfs_rq_of(&p->se);
- __synchronize_entity_decay(&p->se);
- subtract_blocked_load_contrib(cfs_rq,
- p->se.avg.load_avg_contrib);
+ if (se->avg.decay_count) {
+ __synchronize_entity_decay(se);
+ subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib);
}
#endif
}
diff --git a/kernel/smp.c b/kernel/smp.c
index fe9f773..7332697 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -186,25 +186,13 @@ void generic_smp_call_function_single_interrupt(void)
while (!list_empty(&list)) {
struct call_single_data *csd;
- unsigned int csd_flags;
csd = list_entry(list.next, struct call_single_data, list);
list_del(&csd->list);
- /*
- * 'csd' can be invalid after this call if flags == 0
- * (when called through generic_exec_single()),
- * so save them away before making the call:
- */
- csd_flags = csd->flags;
-
csd->func(csd->info);
- /*
- * Unlocked CSDs are valid through generic_exec_single():
- */
- if (csd_flags & CSD_FLAG_LOCK)
- csd_unlock(csd);
+ csd_unlock(csd);
}
}
--
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