Commit 3aef1551 authored by Valentin Schneider's avatar Valentin Schneider Committed by Peter Zijlstra
Browse files

sched: Remove select_task_rq()'s sd_flag parameter 



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: default avatarValentin Schneider <valentin.schneider@arm.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201102184514.2733-3-valentin.schneider@arm.com
parent 17770579

kernel/sched/core.c

+5 −5
Original line number Diff line number Diff line
@@ -2769,12 +2769,12 @@ out: 
 * 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 && !is_migration_disabled(p))

		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);
@@ -3409,7 +3409,7 @@ 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);
@@ -3793,7 +3793,7 @@ 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);
@@ -4384,7 +4384,7 @@ 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;

kernel/sched/deadline.c

+2 −2
Original line number Diff line number Diff line
@@ -1683,13 +1683,13 @@ 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);

kernel/sched/fair.c

+5 −3
Original line number Diff line number Diff line
@@ -6684,7 +6684,7 @@ fail: 


/*

 * 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
@@ -6695,13 +6695,15 @@ fail: 
 * 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);

kernel/sched/idle.c

+1 −1
Original line number Diff line number Diff line
@@ -376,7 +376,7 @@ 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 */

}

kernel/sched/rt.c

+2 −2
Original line number Diff line number Diff line
@@ -1430,14 +1430,14 @@ 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);

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