sched: call resched_task() conditionally from new task wake up path (aec0a514) · Commits · e / devices / android_kernel_xiaomi_markw

- During wake up of a new task, task_new_fair() can do a resched_task() on the current task. Later in the code path, check_preempt_curr() also ends up doing the same, which can be avoided. Check if TIF_NEED_RESCHED is already set for the current task. - task_new_fair() does a resched_task() on the current task unconditionally. This can be done only in case when child runs before the parent. So this is a small speedup. Signed-off-by:

Bharata B Rao <bharata@linux.vnet.ibm.com> Acked-by:

Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by:

Ingo Molnar <mingo@elte.hu>

kernel/sched_fair.c

+8 −1

Original line number	Original line	Diff line number	Diff line
	@@ -1348,6 +1348,13 @@ static void check_preempt_wakeup(struct rq rq, struct task_struct p)
	if (unlikely(se == pse))		if (unlikely(se == pse))
	return;		return;

			/*
			* We can come here with TIF_NEED_RESCHED already set from new task
			* wake up path.
			*/
			if (test_tsk_need_resched(curr))
			return;

	cfs_rq_of(pse)->next = pse;		cfs_rq_of(pse)->next = pse;

	/*		/*
	@@ -1620,10 +1627,10 @@ static void task_new_fair(struct rq rq, struct task_struct p)
	* 'current' within the tree based on its new key value.		* 'current' within the tree based on its new key value.
	*/		*/
	swap(curr->vruntime, se->vruntime);		swap(curr->vruntime, se->vruntime);
			resched_task(rq->curr);
	}		}

	enqueue_task_fair(rq, p, 0);		enqueue_task_fair(rq, p, 0);
	resched_task(rq->curr);
	}		}

	/*		/*