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ANDROID: sched/fair: optimize idle cpu selection for boosted tasks

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find_best_target CPU selection is biased towards lower CPU IDs. Bias
towards higher CPUs for boosted tasks. For boosted tasks unconditionally
use the idle CPU returned by find_best_target.

BUG: 29512132
Change-Id: I3d650051752163fcf3dc7909751d1fde3f9d17c0
Signed-off-by: Andres Oportus <andresoportus@google.com>

Conflicts:
	kernel/sched/fair.c
This commit is contained in:
Todd Kjos
2016-07-29 14:41:25 +01:00
committed by Dmitry Shmidt
parent d248900606
commit 8dce8ebd95
1 changed files with 36 additions and 34 deletions
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70
kernel/sched/fair.c
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@@ -6269,32 +6269,30 @@ done:
return target;
}
static inline int find_best_target(struct task_struct *p)
static inline int find_best_target(struct task_struct *p, bool boosted)
{
int i, boosted;
int iter_cpu;
int target_cpu = -1;
int target_capacity = 0;
int backup_capacity = 0;
int idle_cpu = -1;
int best_idle_cpu = -1;
int best_idle_cstate = INT_MAX;
int backup_cpu = -1;
unsigned long task_util_boosted, new_util;
/*
* Favor 1) busy cpu with most capacity at current OPP
* 2) idle_cpu with capacity at current OPP
* 3) busy cpu with capacity at higher OPP
*/
#ifdef CONFIG_CGROUP_SCHEDTUNE
boosted = schedtune_task_boost(p);
#else
boosted = 0;
#endif
task_util_boosted = boosted_task_util(p);
for_each_cpu(i, tsk_cpus_allowed(p)) {
int cur_capacity = capacity_curr_of(i);
struct rq *rq = cpu_rq(i);
int idle_idx = idle_get_state_idx(rq);
for (iter_cpu = 0; iter_cpu < NR_CPUS; iter_cpu++) {
int cur_capacity;
struct rq *rq;
int idle_idx;
/*
* favor higher cpus for boosted tasks
*/
int i = boosted ? NR_CPUS-iter_cpu-1 : iter_cpu;
if (!cpu_online(i) || !cpumask_test_cpu(i, tsk_cpus_allowed(p)))
continue;
/*
* p's blocked utilization is still accounted for on prev_cpu
@@ -6315,46 +6313,43 @@ static inline int find_best_target(struct task_struct *p)
* For boosted tasks we favor idle cpus unconditionally to
* improve latency.
*/
if (idle_idx >= 0 && boosted) {
if (idle_cpu < 0 ||
(sysctl_sched_cstate_aware &&
best_idle_cstate > idle_idx)) {
best_idle_cstate = idle_idx;
idle_cpu = i;
}
if (idle_cpu(i) && boosted) {
if (best_idle_cpu < 0)
best_idle_cpu = i;
continue;
}
cur_capacity = capacity_curr_of(i);
rq = cpu_rq(i);
idle_idx = idle_get_state_idx(rq);
if (new_util < cur_capacity) {
if (cpu_rq(i)->nr_running) {
if (target_capacity == 0 ||
target_capacity > cur_capacity) {
/* busy CPU with most capacity at current OPP */
target_cpu = i;
target_capacity = cur_capacity;
}
} else if (!boosted) {
if (idle_cpu < 0 ||
if (best_idle_cpu < 0 ||
(sysctl_sched_cstate_aware &&
best_idle_cstate > idle_idx)) {
best_idle_cstate = idle_idx;
idle_cpu = i;
best_idle_cpu = i;
}
}
} else if (backup_capacity == 0 ||
backup_capacity > cur_capacity) {
/* first busy CPU with capacity at higher OPP */
backup_capacity = cur_capacity;
backup_cpu = i;
}
}
if (!boosted && target_cpu < 0) {
target_cpu = idle_cpu >= 0 ? idle_cpu : backup_cpu;
}
if (boosted && best_idle_cpu >= 0)
target_cpu = best_idle_cpu;
else if (target_cpu < 0)
target_cpu = best_idle_cpu >= 0 ? best_idle_cpu : backup_cpu;
if (boosted && idle_cpu >= 0)
target_cpu = idle_cpu;
return target_cpu;
}
@@ -6440,9 +6435,16 @@ static int energy_aware_wake_cpu(struct task_struct *p, int target, int sync)
/*
* Find a cpu with sufficient capacity
*/
int tmp_target = find_best_target(p);
#ifdef CONFIG_CGROUP_SCHEDTUNE
bool boosted = schedtune_task_boost(p) > 0;
#else
bool boosted = 0;
#endif
int tmp_target = find_best_target(p, boosted);
if (tmp_target >= 0)
target_cpu = tmp_target;
if (boosted && idle_cpu(target_cpu))
return target_cpu;
}
if (target_cpu != task_cpu(p)) {