sched/core: Don't skip remote tick for idle CPUs

This will be used in the next patch to get a loadavg update from
nohz cpus.  The delta check is skipped because idle_sched_class
doesn't update se.exec_start.

Signed-off-by: Scott Wood <swood@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/1578736419-14628-2-git-send-email-swood@redhat.com

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fc1dfc0076045dc2bfcb3f0bd9b60e1ec2e7ac09..cf8b33dc451323cbec9796c8ab642745d374b77b 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3669,22 +3669,24 @@ static void sched_tick_remote(struct work_struct *work)
         * statistics and checks timeslices in a time-independent way, regardless
         * of when exactly it is running.
         */
-       if (idle_cpu(cpu) || !tick_nohz_tick_stopped_cpu(cpu))
+       if (!tick_nohz_tick_stopped_cpu(cpu))
                goto out_requeue;
 
        rq_lock_irq(rq, &rf);
        curr = rq->curr;
-       if (is_idle_task(curr) || cpu_is_offline(cpu))
+       if (cpu_is_offline(cpu))
                goto out_unlock;
 
        update_rq_clock(rq);
-       delta = rq_clock_task(rq) - curr->se.exec_start;
 
-       /*
-        * Make sure the next tick runs within a reasonable
-        * amount of time.
-        */
-       WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
+       if (!is_idle_task(curr)) {
+               /*
+                * Make sure the next tick runs within a reasonable
+                * amount of time.
+                */
+               delta = rq_clock_task(rq) - curr->se.exec_start;
+               WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
+       }
        curr->sched_class->task_tick(rq, curr, 0);
 
 out_unlock: