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sched/fair: Simplify idle_idx handling in select_idle_sibling()

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Rename best_idle to best_idle_cpu so the same name is used like in
find_best_target().

Fix if (best_idle > 0) since best_idle_cpu = 0 is a valid target.

Use 'unsigned long' data type for best_idle_capacity.

Since we're looking for the shallowest best_idle_cstate initialize
best_idle_cstate = INT_MAX. For cpus which are not idle (idle_idx = -1)
the condition 'if (idle_idx < best_idle_cstate && ...)' is never
executed.

Change-Id: Ic5b63d58478696b3d1ec6253cf739a69a574cf99
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
(cherry picked from commit 8bff5e9c0968108d465e1f2a4624fc5ec2f00849)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
This commit is contained in:
Dietmar Eggemann 2017-01-16 12:42:59 +00:00 • committed by Andres Oportus
parent b31ae71ef7
commit 4e18c8a10d
1 changed files with 11 additions and 9 deletions
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20
kernel/sched/fair.c
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@ -5677,9 +5677,9 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
{
struct sched_domain *sd;
struct sched_group *sg;
int best_idle = -1;
int best_idle_cstate = -1;
int best_idle_capacity = INT_MAX;
int best_idle_cpu = -1;
int best_idle_cstate = INT_MAX;
unsigned long best_idle_capacity = ULONG_MAX;
if (!sysctl_sched_cstate_aware) {
if (idle_cpu(target))
@ -5706,18 +5706,19 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
if (sysctl_sched_cstate_aware) {
for_each_cpu_and(i, tsk_cpus_allowed(p), sched_group_cpus(sg)) {
struct rq *rq = cpu_rq(i);
int idle_idx = idle_get_state_idx(rq);
int idle_idx = idle_get_state_idx(cpu_rq(i));
unsigned long new_usage = boosted_task_util(p);
unsigned long capacity_orig = capacity_orig_of(i);
if (new_usage > capacity_orig || !idle_cpu(i))
goto next;
if (i == target && new_usage <= capacity_curr_of(target))
return target;
if (best_idle < 0 || (idle_idx < best_idle_cstate && capacity_orig <= best_idle_capacity)) {
best_idle = i;
if (idle_idx < best_idle_cstate &&
capacity_orig <= best_idle_capacity) {
best_idle_cpu = i;
best_idle_cstate = idle_idx;
best_idle_capacity = capacity_orig;
}
@ -5736,8 +5737,9 @@ next:
sg = sg->next;
} while (sg != sd->groups);
}
if (best_idle > 0)
target = best_idle;
if (best_idle_cpu >= 0)
target = best_idle_cpu;
done:
return target;