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sched/fair: Expose newidle_balance()

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For pick_next_task_fair() it is the newidle balance that requires
dropping the rq->lock; provided we do put_prev_task() early, we can
also detect the condition for doing newidle early.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
Link: https://lkml.kernel.org/r/9e3eb1859b946f03d7e500453a885725b68957ba.1559129225.git.vpillai@digitalocean.com
This commit is contained in:
Peter Zijlstra 2019-05-29 20:36:42 +00:00
parent 03b7fad167
commit 5ba553eff0
2 changed files with 12 additions and 10 deletions
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18
kernel/sched/fair.c
View file

@ -3690,8 +3690,6 @@ static inline unsigned long cfs_rq_load_avg(struct cfs_rq *cfs_rq)
return cfs_rq->avg.load_avg;
}
static int idle_balance(struct rq *this_rq, struct rq_flags *rf);
static inline unsigned long task_util(struct task_struct *p)
{
return READ_ONCE(p->se.avg.util_avg);
@ -6878,11 +6876,10 @@ done: __maybe_unused;
return p;
idle:
update_misfit_status(NULL, rq);
new_tasks = idle_balance(rq, rf);
new_tasks = newidle_balance(rq, rf);
/*
* Because idle_balance() releases (and re-acquires) rq->lock, it is
* Because newidle_balance() releases (and re-acquires) rq->lock, it is
* possible for any higher priority task to appear. In that case we
* must re-start the pick_next_entity() loop.
*/
@ -9045,10 +9042,10 @@ out_one_pinned:
ld_moved = 0;
/*
* idle_balance() disregards balance intervals, so we could repeatedly
* reach this code, which would lead to balance_interval skyrocketting
* in a short amount of time. Skip the balance_interval increase logic
* to avoid that.
* newidle_balance() disregards balance intervals, so we could
* repeatedly reach this code, which would lead to balance_interval
* skyrocketting in a short amount of time. Skip the balance_interval
* increase logic to avoid that.
*/
if (env.idle == CPU_NEWLY_IDLE)
goto out;
@ -9758,7 +9755,7 @@ static inline void nohz_newidle_balance(struct rq *this_rq) { }
* idle_balance is called by schedule() if this_cpu is about to become
* idle. Attempts to pull tasks from other CPUs.
*/
static int idle_balance(struct rq *this_rq, struct rq_flags *rf)
int newidle_balance(struct rq *this_rq, struct rq_flags *rf)
{
unsigned long next_balance = jiffies + HZ;
int this_cpu = this_rq->cpu;
@ -9766,6 +9763,7 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf)
int pulled_task = 0;
u64 curr_cost = 0;
update_misfit_status(NULL, this_rq);
/*
* We must set idle_stamp _before_ calling idle_balance(), such that we
* measure the duration of idle_balance() as idle time.

4
kernel/sched/sched.h
View file

@ -1445,10 +1445,14 @@ static inline void unregister_sched_domain_sysctl(void)
}
#endif
extern int newidle_balance(struct rq *this_rq, struct rq_flags *rf);
#else
static inline void sched_ttwu_pending(void) { }
static inline int newidle_balance(struct rq *this_rq, struct rq_flags *rf) { return 0; }
#endif /* CONFIG_SMP */
#include "stats.h"