[PATCH v4 2/3] sched: Remove select_task_rq()'s sd_flag parameter
From: Valentin Schneider
Date: Mon Nov 02 2020 - 13:48:31 EST
Only select_task_rq_fair() uses that parameter to do an actual domain
search, other classes only care about what kind of wakeup is happening
(fork, exec, or "regular") and thus just translate the flag into a wakeup
type.
WF_TTWU and WF_EXEC have just been added, use these along with WF_FORK to
encode the wakeup types we care about. For select_task_rq_fair(), we can
simply use the shiny new WF_flag : SD_flag mapping.
Signed-off-by: Valentin Schneider <valentin.schneider@xxxxxxx>
---
kernel/sched/core.c | 10 +++++-----
kernel/sched/deadline.c | 4 ++--
kernel/sched/fair.c | 8 +++++---
kernel/sched/idle.c | 2 +-
kernel/sched/rt.c | 4 ++--
kernel/sched/sched.h | 2 +-
kernel/sched/stop_task.c | 2 +-
7 files changed, 17 insertions(+), 15 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index d2003a7d5ab5..d31eace9b5e2 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2348,12 +2348,12 @@ static int select_fallback_rq(int cpu, struct task_struct *p)
* The caller (fork, wakeup) owns p->pi_lock, ->cpus_ptr is stable.
*/
static inline
-int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
+int select_task_rq(struct task_struct *p, int cpu, int wake_flags)
{
lockdep_assert_held(&p->pi_lock);
if (p->nr_cpus_allowed > 1)
- cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
+ cpu = p->sched_class->select_task_rq(p, cpu, wake_flags);
else
cpu = cpumask_any(p->cpus_ptr);
@@ -2961,7 +2961,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
*/
smp_cond_load_acquire(&p->on_cpu, !VAL);
- cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
+ cpu = select_task_rq(p, p->wake_cpu, wake_flags | WF_TTWU);
if (task_cpu(p) != cpu) {
wake_flags |= WF_MIGRATED;
psi_ttwu_dequeue(p);
@@ -3344,7 +3344,7 @@ void wake_up_new_task(struct task_struct *p)
*/
p->recent_used_cpu = task_cpu(p);
rseq_migrate(p);
- __set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
+ __set_task_cpu(p, select_task_rq(p, task_cpu(p), WF_FORK));
#endif
rq = __task_rq_lock(p, &rf);
update_rq_clock(rq);
@@ -3888,7 +3888,7 @@ void sched_exec(void)
int dest_cpu;
raw_spin_lock_irqsave(&p->pi_lock, flags);
- dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
+ dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), WF_EXEC);
if (dest_cpu == smp_processor_id())
goto unlock;
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index f232305dcefe..a6933c7f9ba7 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1664,13 +1664,13 @@ static void yield_task_dl(struct rq *rq)
static int find_later_rq(struct task_struct *task);
static int
-select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags)
+select_task_rq_dl(struct task_struct *p, int cpu, int flags)
{
struct task_struct *curr;
bool select_rq;
struct rq *rq;
- if (sd_flag != SD_BALANCE_WAKE)
+ if (!(flags & WF_TTWU))
goto out;
rq = cpu_rq(cpu);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 290f9e38378c..c02f7af0a925 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6663,7 +6663,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
/*
* select_task_rq_fair: Select target runqueue for the waking task in domains
- * that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE,
+ * that have the relevant SD flag set. In practice, this is SD_BALANCE_WAKE,
* SD_BALANCE_FORK, or SD_BALANCE_EXEC.
*
* Balances load by selecting the idlest CPU in the idlest group, or under
@@ -6674,13 +6674,15 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
* preempt must be disabled.
*/
static int
-select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_flags)
+select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags)
{
+ int sync = (wake_flags & WF_SYNC) && !(current->flags & PF_EXITING);
struct sched_domain *tmp, *sd = NULL;
int cpu = smp_processor_id();
int new_cpu = prev_cpu;
int want_affine = 0;
- int sync = (wake_flags & WF_SYNC) && !(current->flags & PF_EXITING);
+ /* SD_flags and WF_flags share the first nibble */
+ int sd_flag = wake_flags & 0xF;
if (sd_flag & SD_BALANCE_WAKE) {
record_wakee(p);
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 24d0ee26377d..56d12d9bbe47 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -375,7 +375,7 @@ void cpu_startup_entry(enum cpuhp_state state)
#ifdef CONFIG_SMP
static int
-select_task_rq_idle(struct task_struct *p, int cpu, int sd_flag, int flags)
+select_task_rq_idle(struct task_struct *p, int cpu, int flags)
{
return task_cpu(p); /* IDLE tasks as never migrated */
}
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 49ec096a8aa1..c3ca1ab9e011 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1428,14 +1428,14 @@ static void yield_task_rt(struct rq *rq)
static int find_lowest_rq(struct task_struct *task);
static int
-select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
+select_task_rq_rt(struct task_struct *p, int cpu, int flags)
{
struct task_struct *curr;
struct rq *rq;
bool test;
/* For anything but wake ups, just return the task_cpu */
- if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
+ if (!(flags & (WF_TTWU | WF_FORK)))
goto out;
rq = cpu_rq(cpu);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 65666c52f347..f6d12c50d454 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1803,7 +1803,7 @@ struct sched_class {
#ifdef CONFIG_SMP
int (*balance)(struct rq *rq, struct task_struct *prev, struct rq_flags *rf);
- int (*select_task_rq)(struct task_struct *p, int task_cpu, int sd_flag, int flags);
+ int (*select_task_rq)(struct task_struct *p, int task_cpu, int flags);
void (*migrate_task_rq)(struct task_struct *p, int new_cpu);
void (*task_woken)(struct rq *this_rq, struct task_struct *task);
diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c
index ceb5b6b12561..c2ddcfee0483 100644
--- a/kernel/sched/stop_task.c
+++ b/kernel/sched/stop_task.c
@@ -11,7 +11,7 @@
#ifdef CONFIG_SMP
static int
-select_task_rq_stop(struct task_struct *p, int cpu, int sd_flag, int flags)
+select_task_rq_stop(struct task_struct *p, int cpu, int flags)
{
return task_cpu(p); /* stop tasks as never migrate */
}
--
2.27.0