sched: Fix task priority bug (57785df5) · Commits · 戴 / test

83f9ac removed a call to effective_prio() in wake_up_new_task(), which leads to tasks running at MAX_PRIO. This is caused by the idle thread being set to MAX_PRIO before forking off init. O(1) used that to make sure idle was always preempted, CFS uses check_preempt_curr_idle() for that so we can savely remove this bit of legacy code. Reported-by:

Mike Galbraith <efault@gmx.de> Tested-by:

Mike Galbraith <efault@gmx.de> Signed-off-by:

Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1259754383.4003.610.camel@laptop> Signed-off-by:

Ingo Molnar <mingo@elte.hu>

kernel/sched.c

+0 −6

Original line number	Diff line number	Diff line
		@@ -3158,10 +3158,6 @@ static void pull_task(struct rq src_rq, struct task_struct p,
		deactivate_task(src_rq, p, 0);
		set_task_cpu(p, this_cpu);
		activate_task(this_rq, p, 0);
		/*
		* Note that idle threads have a prio of MAX_PRIO, for this test
		* to be always true for them.
		*/
		check_preempt_curr(this_rq, p, 0);
		}

		@@ -6992,7 +6988,6 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu)
		__sched_fork(idle);
		idle->se.exec_start = sched_clock();

		idle->prio = idle->normal_prio = MAX_PRIO;
		cpumask_copy(&idle->cpus_allowed, cpumask_of(cpu));
		__set_task_cpu(idle, cpu);

		@@ -7696,7 +7691,6 @@ migration_call(struct notifier_block nfb, unsigned long action, void hcpu)
		spin_lock_irq(&rq->lock);
		update_rq_clock(rq);
		deactivate_task(rq, rq->idle, 0);
		rq->idle->static_prio = MAX_PRIO;
		__setscheduler(rq, rq->idle, SCHED_NORMAL, 0);
		rq->idle->sched_class = &idle_sched_class;
		migrate_dead_tasks(cpu);

Admin message