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sched: Rename load-balancing fields
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 s/env->this_/env->dst_/g
 s/env->busiest_/env->src_/g
 s/pull_task/move_task/g

Makes everything clearer.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: pjt@google.com
Link: http://lkml.kernel.org/n/tip-0yvgms8t8x962drpvl0fu0kk@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 8e45cb5 commit ddcdf6e
Showing 1 changed file with 60 additions and 58 deletions.
118 changes: 60 additions & 58 deletions kernel/sched/fair.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2918,7 +2918,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
return;

/*
* This is possible from callers such as pull_task(), in which we
* This is possible from callers such as move_task(), in which we
* unconditionally check_prempt_curr() after an enqueue (which may have
* lead to a throttle). This both saves work and prevents false
* next-buddy nomination below.
Expand Down Expand Up @@ -3084,17 +3084,37 @@ static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preemp

static unsigned long __read_mostly max_load_balance_interval = HZ/10;

#define LBF_ALL_PINNED 0x01
#define LBF_NEED_BREAK 0x02 /* clears into HAD_BREAK */
#define LBF_HAD_BREAK 0x04
#define LBF_HAD_BREAKS 0x0C /* count HAD_BREAKs overflows into ABORT */
#define LBF_ABORT 0x10

struct lb_env {
struct sched_domain *sd;

int src_cpu;
struct rq *src_rq;
struct cfs_rq *src_cfs_rq;

int dst_cpu;
struct rq *dst_rq;

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

/*
* pull_task - move a task from a remote runqueue to the local runqueue.
* move_task - move a task from one runqueue to another runqueue.
* Both runqueues must be locked.
*/
static void pull_task(struct rq *src_rq, struct task_struct *p,
struct rq *this_rq, int this_cpu)
static void move_task(struct task_struct *p, struct lb_env *env)
{
deactivate_task(src_rq, p, 0);
set_task_cpu(p, this_cpu);
activate_task(this_rq, p, 0);
check_preempt_curr(this_rq, p, 0);
deactivate_task(env->src_rq, p, 0);
set_task_cpu(p, env->dst_cpu);
activate_task(env->dst_rq, p, 0);
check_preempt_curr(env->dst_rq, p, 0);
}

/*
Expand Down Expand Up @@ -3129,26 +3149,6 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
return delta < (s64)sysctl_sched_migration_cost;
}

#define LBF_ALL_PINNED 0x01
#define LBF_NEED_BREAK 0x02 /* clears into HAD_BREAK */
#define LBF_HAD_BREAK 0x04
#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?
*/
Expand All @@ -3162,13 +3162,13 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
* 2) cannot be migrated to this CPU due to cpus_allowed, or
* 3) are cache-hot on their current CPU.
*/
if (!cpumask_test_cpu(env->this_cpu, tsk_cpus_allowed(p))) {
if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) {
schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
return 0;
}
env->flags &= ~LBF_ALL_PINNED;

if (task_running(env->busiest_rq, p)) {
if (task_running(env->src_rq, p)) {
schedstat_inc(p, se.statistics.nr_failed_migrations_running);
return 0;
}
Expand All @@ -3179,7 +3179,7 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
* 2) too many balance attempts have failed.
*/

tsk_cache_hot = task_hot(p, env->busiest_rq->clock_task, env->sd);
tsk_cache_hot = task_hot(p, env->src_rq->clock_task, env->sd);
if (!tsk_cache_hot ||
env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
#ifdef CONFIG_SCHEDSTATS
Expand Down Expand Up @@ -3210,20 +3210,20 @@ static int move_one_task(struct lb_env *env)
struct task_struct *p, *n;
struct cfs_rq *cfs_rq;

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

if (!can_migrate_task(p, env))
continue;

pull_task(env->busiest_rq, p, env->this_rq, env->this_cpu);
move_task(p, env);
/*
* 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().
* Right now, this is only the second place move_task()
* is called, so we can safely collect move_task()
* stats here rather than inside move_task().
*/
schedstat_inc(env->sd, lb_gained[env->idle]);
return 1;
Expand All @@ -3242,7 +3242,7 @@ static unsigned long balance_tasks(struct lb_env *env)
if (env->max_load_move == 0)
goto out;

list_for_each_entry_safe(p, n, &env->busiest_cfs_rq->tasks, se.group_node) {
list_for_each_entry_safe(p, n, &env->src_cfs_rq->tasks, se.group_node) {
if (loops++ > sysctl_sched_nr_migrate) {
env->flags |= LBF_NEED_BREAK;
break;
Expand All @@ -3252,7 +3252,7 @@ static unsigned long balance_tasks(struct lb_env *env)
!can_migrate_task(p, env))
continue;

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

Expand All @@ -3277,9 +3277,9 @@ static unsigned long balance_tasks(struct lb_env *env)
}
out:
/*
* Right now, this is one of only two places pull_task() is called,
* so we can safely collect pull_task() stats here rather than
* inside pull_task().
* Right now, this is one of only two places move_task() is called,
* so we can safely collect move_task() stats here rather than
* inside move_task().
*/
schedstat_add(env->sd, lb_gained[env->idle], pulled);

Expand Down Expand Up @@ -3372,11 +3372,11 @@ static unsigned long load_balance_fair(struct lb_env *env)
long rem_load_move = env->max_load_move;

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

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

if (env->flags & (LBF_NEED_BREAK|LBF_ABORT))
Expand All @@ -3385,12 +3385,12 @@ static unsigned long load_balance_fair(struct lb_env *env)
/*
* empty group or part of a throttled hierarchy
*/
if (!env->busiest_cfs_rq->task_weight)
if (!env->src_cfs_rq->task_weight)
continue;

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

rem_load = (u64)rem_load_move * busiest_weight;
Expand Down Expand Up @@ -3420,7 +3420,7 @@ static inline void update_shares(int cpu)

static unsigned long load_balance_fair(struct lb_env *env)
{
env->busiest_cfs_rq = &env->busiest_rq->cfs;
env->src_cfs_rq = &env->src_rq->cfs;
return balance_tasks(env);
}
#endif
Expand Down Expand Up @@ -3451,7 +3451,7 @@ static int move_tasks(struct lb_env *env)
* kernels will stop after the first task is pulled to minimize
* the critical section.
*/
if (env->idle == CPU_NEWLY_IDLE && env->this_rq->nr_running) {
if (env->idle == CPU_NEWLY_IDLE && env->dst_rq->nr_running) {
env->flags |= LBF_ABORT;
break;
}
Expand Down Expand Up @@ -4461,8 +4461,8 @@ static int load_balance(int this_cpu, struct rq *this_rq,

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

Expand Down Expand Up @@ -4502,7 +4502,8 @@ static int load_balance(int this_cpu, struct rq *this_rq,
*/
env.flags |= LBF_ALL_PINNED;
env.max_load_move = imbalance;
env.busiest_rq = busiest;
env.src_cpu = busiest->cpu;
env.src_rq = busiest;

local_irq_save(flags);
double_rq_lock(this_rq, busiest);
Expand Down Expand Up @@ -4722,9 +4723,10 @@ 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,
.dst_cpu = target_cpu,
.dst_rq = target_rq,
.src_cpu = busiest_rq->cpu,
.src_rq = busiest_rq,
.idle = CPU_IDLE,
};

Expand Down

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