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sched: Move load-balancing arguments into helper struct
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Passing large sets of similar arguments all around the load-balancer
gets tiresom when you want to modify something. Stick them all in a
helper structure and pass the structure around.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: pjt@google.com
Link: http://lkml.kernel.org/n/tip-5slqz0vhsdzewrfk9eza1aon@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Peter Zijlstra authored and Ingo Molnar committed Mar 1, 2012
1 parent 3c7d518 commit 8e45cb5
Showing 1 changed file with 93 additions and 84 deletions.
177 changes: 93 additions & 84 deletions kernel/sched/fair.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3135,13 +3135,25 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
#define LBF_HAD_BREAKS 0x0C /* count HAD_BREAKs overflows into ABORT */
#define LBF_ABORT 0x10

struct lb_env {
struct sched_domain *sd;

int this_cpu;
struct rq *this_rq;

struct rq *busiest_rq;
struct cfs_rq *busiest_cfs_rq;

enum cpu_idle_type idle;
unsigned long max_load_move;
unsigned int flags;
};

/*
* can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
*/
static
int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
struct sched_domain *sd, enum cpu_idle_type idle,
int *lb_flags)
int can_migrate_task(struct task_struct *p, struct lb_env *env)
{
int tsk_cache_hot = 0;
/*
Expand All @@ -3150,13 +3162,13 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
* 2) cannot be migrated to this CPU due to cpus_allowed, or
* 3) are cache-hot on their current CPU.
*/
if (!cpumask_test_cpu(this_cpu, tsk_cpus_allowed(p))) {
if (!cpumask_test_cpu(env->this_cpu, tsk_cpus_allowed(p))) {
schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
return 0;
}
*lb_flags &= ~LBF_ALL_PINNED;
env->flags &= ~LBF_ALL_PINNED;

if (task_running(rq, p)) {
if (task_running(env->busiest_rq, p)) {
schedstat_inc(p, se.statistics.nr_failed_migrations_running);
return 0;
}
Expand All @@ -3167,12 +3179,12 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
* 2) too many balance attempts have failed.
*/

tsk_cache_hot = task_hot(p, rq->clock_task, sd);
tsk_cache_hot = task_hot(p, env->busiest_rq->clock_task, env->sd);
if (!tsk_cache_hot ||
sd->nr_balance_failed > sd->cache_nice_tries) {
env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
#ifdef CONFIG_SCHEDSTATS
if (tsk_cache_hot) {
schedstat_inc(sd, lb_hot_gained[idle]);
schedstat_inc(env->sd, lb_hot_gained[env->idle]);
schedstat_inc(p, se.statistics.nr_forced_migrations);
}
#endif
Expand All @@ -3193,63 +3205,54 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
*
* Called with both runqueues locked.
*/
static int
move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
struct sched_domain *sd, enum cpu_idle_type idle)
static int move_one_task(struct lb_env *env)
{
struct task_struct *p, *n;
struct cfs_rq *cfs_rq;
int pinned = 0;

for_each_leaf_cfs_rq(busiest, cfs_rq) {
for_each_leaf_cfs_rq(env->busiest_rq, cfs_rq) {
list_for_each_entry_safe(p, n, &cfs_rq->tasks, se.group_node) {
if (throttled_lb_pair(task_group(p),
busiest->cpu, this_cpu))
env->busiest_rq->cpu, env->this_cpu))
break;

if (!can_migrate_task(p, busiest, this_cpu,
sd, idle, &pinned))
if (!can_migrate_task(p, env))
continue;

pull_task(busiest, p, this_rq, this_cpu);
pull_task(env->busiest_rq, p, env->this_rq, env->this_cpu);
/*
* Right now, this is only the second place pull_task()
* is called, so we can safely collect pull_task()
* stats here rather than inside pull_task().
*/
schedstat_inc(sd, lb_gained[idle]);
schedstat_inc(env->sd, lb_gained[env->idle]);
return 1;
}
}

return 0;
}

static unsigned long
balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
unsigned long max_load_move, struct sched_domain *sd,
enum cpu_idle_type idle, int *lb_flags,
struct cfs_rq *busiest_cfs_rq)
static unsigned long balance_tasks(struct lb_env *env)
{
int loops = 0, pulled = 0;
long rem_load_move = max_load_move;
long rem_load_move = env->max_load_move;
struct task_struct *p, *n;

if (max_load_move == 0)
if (env->max_load_move == 0)
goto out;

list_for_each_entry_safe(p, n, &busiest_cfs_rq->tasks, se.group_node) {
list_for_each_entry_safe(p, n, &env->busiest_cfs_rq->tasks, se.group_node) {
if (loops++ > sysctl_sched_nr_migrate) {
*lb_flags |= LBF_NEED_BREAK;
env->flags |= LBF_NEED_BREAK;
break;
}

if ((p->se.load.weight >> 1) > rem_load_move ||
!can_migrate_task(p, busiest, this_cpu, sd, idle,
lb_flags))
!can_migrate_task(p, env))
continue;

pull_task(busiest, p, this_rq, this_cpu);
pull_task(env->busiest_rq, p, env->this_rq, env->this_cpu);
pulled++;
rem_load_move -= p->se.load.weight;

Expand All @@ -3259,8 +3262,8 @@ balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
* kernels will stop after the first task is pulled to minimize
* the critical section.
*/
if (idle == CPU_NEWLY_IDLE) {
*lb_flags |= LBF_ABORT;
if (env->idle == CPU_NEWLY_IDLE) {
env->flags |= LBF_ABORT;
break;
}
#endif
Expand All @@ -3278,9 +3281,9 @@ balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
* so we can safely collect pull_task() stats here rather than
* inside pull_task().
*/
schedstat_add(sd, lb_gained[idle], pulled);
schedstat_add(env->sd, lb_gained[env->idle], pulled);

return max_load_move - rem_load_move;
return env->max_load_move - rem_load_move;
}

#ifdef CONFIG_FAIR_GROUP_SCHED
Expand Down Expand Up @@ -3363,40 +3366,39 @@ static void update_h_load(long cpu)
walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
}

static unsigned long
load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
unsigned long max_load_move,
struct sched_domain *sd, enum cpu_idle_type idle,
int *lb_flags)
static unsigned long load_balance_fair(struct lb_env *env)
{
long rem_load_move = max_load_move;
struct cfs_rq *busiest_cfs_rq;
unsigned long max_load_move = env->max_load_move;
long rem_load_move = env->max_load_move;

rcu_read_lock();
update_h_load(cpu_of(busiest));
update_h_load(cpu_of(env->busiest_rq));

for_each_leaf_cfs_rq(busiest, busiest_cfs_rq) {
unsigned long busiest_h_load = busiest_cfs_rq->h_load;
unsigned long busiest_weight = busiest_cfs_rq->load.weight;
for_each_leaf_cfs_rq(env->busiest_rq, env->busiest_cfs_rq) {
unsigned long busiest_h_load = env->busiest_cfs_rq->h_load;
unsigned long busiest_weight = env->busiest_cfs_rq->load.weight;
u64 rem_load, moved_load;

if (*lb_flags & (LBF_NEED_BREAK|LBF_ABORT))
if (env->flags & (LBF_NEED_BREAK|LBF_ABORT))
break;

/*
* empty group or part of a throttled hierarchy
*/
if (!busiest_cfs_rq->task_weight ||
throttled_lb_pair(busiest_cfs_rq->tg, cpu_of(busiest), this_cpu))
if (!env->busiest_cfs_rq->task_weight)
continue;

if (throttled_lb_pair(env->busiest_cfs_rq->tg,
cpu_of(env->busiest_rq),
env->this_cpu))
continue;

rem_load = (u64)rem_load_move * busiest_weight;
rem_load = div_u64(rem_load, busiest_h_load + 1);

moved_load = balance_tasks(this_rq, this_cpu, busiest,
rem_load, sd, idle, lb_flags,
busiest_cfs_rq);
env->max_load_move = rem_load;

moved_load = balance_tasks(env);
if (!moved_load)
continue;

Expand All @@ -3416,15 +3418,10 @@ static inline void update_shares(int cpu)
{
}

static unsigned long
load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
unsigned long max_load_move,
struct sched_domain *sd, enum cpu_idle_type idle,
int *lb_flags)
static unsigned long load_balance_fair(struct lb_env *env)
{
return balance_tasks(this_rq, this_cpu, busiest,
max_load_move, sd, idle, lb_flags,
&busiest->cfs);
env->busiest_cfs_rq = &env->busiest_rq->cfs;
return balance_tasks(env);
}
#endif

Expand All @@ -3435,21 +3432,17 @@ load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
*
* Called with both runqueues locked.
*/
static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
unsigned long max_load_move,
struct sched_domain *sd, enum cpu_idle_type idle,
int *lb_flags)
static int move_tasks(struct lb_env *env)
{
unsigned long max_load_move = env->max_load_move;
unsigned long total_load_moved = 0, load_moved;

do {
load_moved = load_balance_fair(this_rq, this_cpu, busiest,
max_load_move - total_load_moved,
sd, idle, lb_flags);

env->max_load_move = max_load_move - total_load_moved;
load_moved = load_balance_fair(env);
total_load_moved += load_moved;

if (*lb_flags & (LBF_NEED_BREAK|LBF_ABORT))
if (env->flags & (LBF_NEED_BREAK|LBF_ABORT))
break;

#ifdef CONFIG_PREEMPT
Expand All @@ -3458,8 +3451,8 @@ static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
* kernels will stop after the first task is pulled to minimize
* the critical section.
*/
if (idle == CPU_NEWLY_IDLE && this_rq->nr_running) {
*lb_flags |= LBF_ABORT;
if (env->idle == CPU_NEWLY_IDLE && env->this_rq->nr_running) {
env->flags |= LBF_ABORT;
break;
}
#endif
Expand Down Expand Up @@ -4459,13 +4452,20 @@ static int load_balance(int this_cpu, struct rq *this_rq,
struct sched_domain *sd, enum cpu_idle_type idle,
int *balance)
{
int ld_moved, lb_flags = 0, active_balance = 0;
int ld_moved, active_balance = 0;
struct sched_group *group;
unsigned long imbalance;
struct rq *busiest;
unsigned long flags;
struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);

struct lb_env env = {
.sd = sd,
.this_cpu = this_cpu,
.this_rq = this_rq,
.idle = idle,
};

cpumask_copy(cpus, cpu_active_mask);

schedstat_inc(sd, lb_count[idle]);
Expand Down Expand Up @@ -4500,11 +4500,13 @@ static int load_balance(int this_cpu, struct rq *this_rq,
* still unbalanced. ld_moved simply stays zero, so it is
* correctly treated as an imbalance.
*/
lb_flags |= LBF_ALL_PINNED;
env.flags |= LBF_ALL_PINNED;
env.max_load_move = imbalance;
env.busiest_rq = busiest;

local_irq_save(flags);
double_rq_lock(this_rq, busiest);
ld_moved = move_tasks(this_rq, this_cpu, busiest,
imbalance, sd, idle, &lb_flags);
ld_moved = move_tasks(&env);
double_rq_unlock(this_rq, busiest);
local_irq_restore(flags);

Expand All @@ -4514,18 +4516,18 @@ static int load_balance(int this_cpu, struct rq *this_rq,
if (ld_moved && this_cpu != smp_processor_id())
resched_cpu(this_cpu);

if (lb_flags & LBF_ABORT)
if (env.flags & LBF_ABORT)
goto out_balanced;

if (lb_flags & LBF_NEED_BREAK) {
lb_flags += LBF_HAD_BREAK - LBF_NEED_BREAK;
if (lb_flags & LBF_ABORT)
if (env.flags & LBF_NEED_BREAK) {
env.flags += LBF_HAD_BREAK - LBF_NEED_BREAK;
if (env.flags & LBF_ABORT)
goto out_balanced;
goto redo;
}

/* All tasks on this runqueue were pinned by CPU affinity */
if (unlikely(lb_flags & LBF_ALL_PINNED)) {
if (unlikely(env.flags & LBF_ALL_PINNED)) {
cpumask_clear_cpu(cpu_of(busiest), cpus);
if (!cpumask_empty(cpus))
goto redo;
Expand Down Expand Up @@ -4555,7 +4557,7 @@ static int load_balance(int this_cpu, struct rq *this_rq,
tsk_cpus_allowed(busiest->curr))) {
raw_spin_unlock_irqrestore(&busiest->lock,
flags);
lb_flags |= LBF_ALL_PINNED;
env.flags |= LBF_ALL_PINNED;
goto out_one_pinned;
}

Expand Down Expand Up @@ -4608,7 +4610,7 @@ static int load_balance(int this_cpu, struct rq *this_rq,

out_one_pinned:
/* tune up the balancing interval */
if (((lb_flags & LBF_ALL_PINNED) &&
if (((env.flags & LBF_ALL_PINNED) &&
sd->balance_interval < MAX_PINNED_INTERVAL) ||
(sd->balance_interval < sd->max_interval))
sd->balance_interval *= 2;
Expand Down Expand Up @@ -4718,10 +4720,17 @@ static int active_load_balance_cpu_stop(void *data)
}

if (likely(sd)) {
struct lb_env env = {
.sd = sd,
.this_cpu = target_cpu,
.this_rq = target_rq,
.busiest_rq = busiest_rq,
.idle = CPU_IDLE,
};

schedstat_inc(sd, alb_count);

if (move_one_task(target_rq, target_cpu, busiest_rq,
sd, CPU_IDLE))
if (move_one_task(&env))
schedstat_inc(sd, alb_pushed);
else
schedstat_inc(sd, alb_failed);
Expand Down

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