tick/nohz: Call tick_nohz_task_switch() with interrupts disabled

Call tick_nohz_task_switch() slightly earlier after the context switch
to benefit from disabled IRQs. This way the function doesn't need to
disable them once more.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210512232924.150322-10-frederic@kernel.org

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 78e480f..8f86ac2 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4212,6 +4212,7 @@ static struct rq *finish_task_switch(struct task_struct *prev)
        vtime_task_switch(prev);
        perf_event_task_sched_in(prev, current);
        finish_task(prev);
+       tick_nohz_task_switch();
        finish_lock_switch(rq);
        finish_arch_post_lock_switch();
        kcov_finish_switch(current);
@@ -4257,7 +4258,6 @@ static struct rq *finish_task_switch(struct task_struct *prev)
                put_task_struct_rcu_user(prev);
        }
 
-       tick_nohz_task_switch();
        return rq;
 }
 

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 197a3bd..6ea619d 100644 (file)
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -487,13 +487,10 @@ void tick_nohz_dep_clear_signal(struct signal_struct *sig, enum tick_dep_bits bi
  */
 void __tick_nohz_task_switch(void)
 {
-       unsigned long flags;
        struct tick_sched *ts;
 
-       local_irq_save(flags);
-
        if (!tick_nohz_full_cpu(smp_processor_id()))
-               goto out;
+               return;
 
        ts = this_cpu_ptr(&tick_cpu_sched);
 
@@ -502,8 +499,6 @@ void __tick_nohz_task_switch(void)
                    atomic_read(&current->signal->tick_dep_mask))
                        tick_nohz_full_kick();
        }
-out:
-       local_irq_restore(flags);
 }
 
 /* Get the boot-time nohz CPU list from the kernel parameters. */