sched/core: Simplify update_rq_clock() in __schedule() (bce4dc80) · Commits · 戴 / test

Instead of relying on deactivate_task() to call update_rq_clock() and handling the case where it didn't happen (task_on_rq_queued), unconditionally do update_rq_clock() and skip any further updates. This also avoids a double update on deactivate_task() + ttwu_local(). Signed-off-by:

Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by:

Ingo Molnar <mingo@kernel.org>

kernel/sched/core.c

+3 −5

Original line number	Diff line number	Diff line
		@@ -2114,7 +2114,7 @@ static void try_to_wake_up_local(struct task_struct p, struct rq_flags rf)
		delayacct_blkio_end();
		atomic_dec(&rq->nr_iowait);
		}
		ttwu_activate(rq, p, ENQUEUE_WAKEUP);
		ttwu_activate(rq, p, ENQUEUE_WAKEUP \| ENQUEUE_NOCLOCK);
		}

		ttwu_do_wakeup(rq, p, 0, rf);
		@@ -3393,13 +3393,14 @@ static void __sched notrace __schedule(bool preempt)

		/* Promote REQ to ACT */
		rq->clock_update_flags <<= 1;
		update_rq_clock(rq);

		switch_count = &prev->nivcsw;
		if (!preempt && prev->state) {
		if (unlikely(signal_pending_state(prev->state, prev))) {
		prev->state = TASK_RUNNING;
		} else {
		deactivate_task(rq, prev, DEQUEUE_SLEEP);
		deactivate_task(rq, prev, DEQUEUE_SLEEP \| DEQUEUE_NOCLOCK);
		prev->on_rq = 0;

		if (prev->in_iowait) {
		@@ -3423,9 +3424,6 @@ static void __sched notrace __schedule(bool preempt)
		switch_count = &prev->nvcsw;
		}

		if (task_on_rq_queued(prev))
		update_rq_clock(rq);

		next = pick_next_task(rq, prev, &rf);
		clear_tsk_need_resched(prev);
		clear_preempt_need_resched();

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