sched: Rename load-balancing fields

 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>

1 files changed, 60 insertions, 58 deletions

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 55b1f117419..233d05171bf 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -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.
@@ -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);
 }
 
 /*
@@ -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?
  */
@@ -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;
         }
@@ -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
@@ -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;
@@ -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;
@@ -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;
 
@@ -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);
 
@@ -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))
@@ -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;
@@ -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
@@ -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;
                 }
@@ -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,
         };
 
@@ -4502,7 +4502,8 @@ redo:
                  */
                 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);
@@ -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,
                 };