redonkable/alistair23-linux
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sched: Fix task priority bug

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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>
This commit is contained in:
Peter Zijlstra 2009-12-04 09:59:02 +01:00 committed by Ingo Molnar
parent cd8ad40de3
commit 57785df5ac
1 changed files with 0 additions and 6 deletions
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6
kernel/sched.c
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@ -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);