diff options
| -rw-r--r-- | kernel/sched/core.c | 11 | ||||
| -rw-r--r-- | kernel/sched/fair.c | 14 | ||||
| -rw-r--r-- | kernel/sched/sched.h | 13 |
3 files changed, 27 insertions, 11 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 89e54f3ed571..1a9983da4408 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1447,17 +1447,6 @@ void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) #ifdef CONFIG_SMP -static inline bool is_per_cpu_kthread(struct task_struct *p) -{ - if (!(p->flags & PF_KTHREAD)) - return false; - - if (p->nr_cpus_allowed != 1) - return false; - - return true; -} - /* * Per-CPU kthreads are allowed to run on !active && online CPUs, see * __set_cpus_allowed_ptr() and select_fallback_rq(). diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 25dffc03f0f6..94c3b8469cf6 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5912,6 +5912,20 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) (available_idle_cpu(prev) || sched_idle_cpu(prev))) return prev; + /* + * Allow a per-cpu kthread to stack with the wakee if the + * kworker thread and the tasks previous CPUs are the same. + * The assumption is that the wakee queued work for the + * per-cpu kthread that is now complete and the wakeup is + * essentially a sync wakeup. An obvious example of this + * pattern is IO completions. + */ + if (is_per_cpu_kthread(current) && + prev == smp_processor_id() && + this_rq()->nr_running <= 1) { + return prev; + } + /* Check a recently used CPU as a potential idle candidate: */ recent_used_cpu = p->recent_used_cpu; if (recent_used_cpu != prev && diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 1a88dc8ad11b..5876e6ba5903 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -2479,3 +2479,16 @@ static inline void membarrier_switch_mm(struct rq *rq, { } #endif + +#ifdef CONFIG_SMP +static inline bool is_per_cpu_kthread(struct task_struct *p) +{ + if (!(p->flags & PF_KTHREAD)) + return false; + + if (p->nr_cpus_allowed != 1) + return false; + + return true; +} +#endif |