diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-11-27 17:32:46 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-09-20 13:17:59 -0700 |
| commit | f70cad0fdf30b751216b9ce73d6df3f8aaa3c0fe (patch) | |
| tree | 9659ac466d01340ad461772a8a4d3b71d25caa95 /kernel/sched_fair.c | |
| parent | 7b8a5273c87b4229bb83bbb1282424e2af0af214 (diff) | |
sched: Sanitize fork() handling
commit cd29fe6f2637cc2ccbda5ac65f5332d6bf5fa3c6 upstream
Currently we try to do task placement in wake_up_new_task() after we do
the load-balance pass in sched_fork(). This yields complicated semantics
in that we have to deal with tasks on different RQs and the
set_task_cpu() calls in copy_process() and sched_fork()
Rename ->task_new() to ->task_fork() and call it from sched_fork()
before the balancing, this gives the policy a clear point to place the
task.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'kernel/sched_fair.c')
| -rw-r--r-- | kernel/sched_fair.c | 28 |
1 files changed, 15 insertions, 13 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 803a9d2afcfa..4815f9de2d57 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1911,28 +1911,30 @@ static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued) } /* - * Share the fairness runtime between parent and child, thus the - * total amount of pressure for CPU stays equal - new tasks - * get a chance to run but frequent forkers are not allowed to - * monopolize the CPU. Note: the parent runqueue is locked, - * the child is not running yet. + * called on fork with the child task as argument from the parent's context + * - child not yet on the tasklist + * - preemption disabled */ -static void task_new_fair(struct rq *rq, struct task_struct *p) +static void task_fork_fair(struct task_struct *p) { - struct cfs_rq *cfs_rq = task_cfs_rq(p); + struct cfs_rq *cfs_rq = task_cfs_rq(current); struct sched_entity *se = &p->se, *curr = cfs_rq->curr; int this_cpu = smp_processor_id(); + struct rq *rq = this_rq(); + unsigned long flags; + + spin_lock_irqsave(&rq->lock, flags); - sched_info_queued(p); + if (unlikely(task_cpu(p) != this_cpu)) + __set_task_cpu(p, this_cpu); update_curr(cfs_rq); + if (curr) se->vruntime = curr->vruntime; place_entity(cfs_rq, se, 1); - /* 'curr' will be NULL if the child belongs to a different group */ - if (sysctl_sched_child_runs_first && this_cpu == task_cpu(p) && - curr && entity_before(curr, se)) { + if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) { /* * Upon rescheduling, sched_class::put_prev_task() will place * 'current' within the tree based on its new key value. @@ -1941,7 +1943,7 @@ static void task_new_fair(struct rq *rq, struct task_struct *p) resched_task(rq->curr); } - enqueue_task_fair(rq, p, 0); + spin_unlock_irqrestore(&rq->lock, flags); } /* @@ -2043,7 +2045,7 @@ static const struct sched_class fair_sched_class = { .set_curr_task = set_curr_task_fair, .task_tick = task_tick_fair, - .task_new = task_new_fair, + .task_fork = task_fork_fair, .prio_changed = prio_changed_fair, .switched_to = switched_to_fair, |