Messages in this thread Patch in this message | | | From | Cruz Zhao <> | Subject | [PATCH v2] sched/core: introduce sched_core_idle_cpu() | Date | Sun, 25 Jun 2023 02:28:15 +0800 |
| |
As core scheduling introduced, a new state of idle is defined as force idle, running idle task but nr_running greater than zero.
If a cpu is in force idle state, idle_cpu() will return zero. This result makes sense in certain scenarios, e.g., load balance. but this will cause error in other scenarios, e.g., tick_irq_exit() will not change ts->idle_active back to 1 because idle_cpu() returns 0 when force idle.
To solve this problem, we introduce sched_core_idle_cpu(), which returns 1 when force idle. We audit all users of idle_cpu(), and change idle_cpu() into sched_core_idle_cpu() in the following functions: - showacpu() - rcu_is_rcuc_kthread_starving() - tick_irq_exit()
v1-->v2: replace idle_cpu() with sched_core_idle_cpu() in function showacpu() and rcu_is_rcuc_kthread_starving()
Signed-off-by: Cruz Zhao <CruzZhao@linux.alibaba.com> --- drivers/tty/sysrq.c | 2 +- include/linux/sched.h | 2 ++ kernel/rcu/tree_stall.h | 2 +- kernel/sched/core.c | 13 +++++++++++++ kernel/softirq.c | 2 +- 5 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index b6e70c5cfa17..8a6586800385 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -232,7 +232,7 @@ static void showacpu(void *dummy) unsigned long flags; /* Idle CPUs have no interesting backtrace. */ - if (idle_cpu(smp_processor_id())) { + if (sched_core_idle_cpu(smp_processor_id())) { pr_info("CPU%d: backtrace skipped as idling\n", smp_processor_id()); return; } diff --git a/include/linux/sched.h b/include/linux/sched.h index b09a83bfad8b..73e61c0f10a7 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2430,9 +2430,11 @@ extern void sched_core_free(struct task_struct *tsk); extern void sched_core_fork(struct task_struct *p); extern int sched_core_share_pid(unsigned int cmd, pid_t pid, enum pid_type type, unsigned long uaddr); +extern int sched_core_idle_cpu(int cpu); #else static inline void sched_core_free(struct task_struct *tsk) { } static inline void sched_core_fork(struct task_struct *p) { } +static inline int sched_core_idle_cpu(int cpu) { return idle_cpu(cpu); } #endif extern void sched_set_stop_task(int cpu, struct task_struct *stop); diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index b10b8349bb2a..6169faf30ecd 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -418,7 +418,7 @@ static bool rcu_is_rcuc_kthread_starving(struct rcu_data *rdp, unsigned long *jp return false; cpu = task_cpu(rcuc); - if (cpu_is_offline(cpu) || idle_cpu(cpu)) + if (cpu_is_offline(cpu) || sched_core_idle_cpu(cpu)) return false; j = jiffies - READ_ONCE(rdp->rcuc_activity); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 71c1a0f232b4..c80088956987 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7286,6 +7286,19 @@ struct task_struct *idle_task(int cpu) return cpu_rq(cpu)->idle; } +#ifdef CONFIG_SCHED_CORE +int sched_core_idle_cpu(int cpu) +{ + struct rq *rq = cpu_rq(cpu); + + if (sched_core_enabled(rq) && rq->curr == rq->idle) + return 1; + + return idle_cpu(cpu); +} + +#endif + #ifdef CONFIG_SMP /* * This function computes an effective utilization for the given CPU, to be diff --git a/kernel/softirq.c b/kernel/softirq.c index c8a6913c067d..98b98991ce45 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -630,7 +630,7 @@ static inline void tick_irq_exit(void) int cpu = smp_processor_id(); /* Make sure that timer wheel updates are propagated */ - if ((idle_cpu(cpu) && !need_resched()) || tick_nohz_full_cpu(cpu)) { + if ((sched_core_idle_cpu(cpu) && !need_resched()) || tick_nohz_full_cpu(cpu)) { if (!in_hardirq()) tick_nohz_irq_exit(); } -- 2.27.0
| |