Peter Zijlstra wrote:
On Thu, 2008-07-03 at 15:37 -0600, Gregory Haskins wrote:commit 62fb185130e4d420f71a30ff59d8b16b74ef5d2b reverted some patches in the scheduler, but it looks like it may have left a few redundant calls to inc_load/dec_load remain in set_user_nice (since the dequeue_task/enqueue_task take care of the load. This could result in the load values being off since the load may change while dequeued.I just checked out v2.6.25.10 but cannot see dequeue_task() do it.
Indeed. I think my eyes glazed over the dequeue vs deactivate, and enqueue vs activate. Good catch, and sorry for the noise. I was wrong..
Please ignore this patch. -Greg
deactivate_task() otoh does do it. static void dequeue_task(struct rq *rq, struct task_struct *p, int sleep) { p->sched_class->dequeue_task(rq, p, sleep); p->se.on_rq = 0; } vs static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep) { if (task_contributes_to_load(p)) rq->nr_uninterruptible++; dequeue_task(rq, p, sleep); dec_nr_running(p, rq); } where static void dec_nr_running(struct task_struct *p, struct rq *rq) { rq->nr_running--; dec_load(rq, p); } And since set_user_nice() actually changes the load we'd better not forget to do this dec/inc load stuff. So I'm thinking this patch would actually break stuff.Signed-off-by: Gregory Haskins <ghaskins@xxxxxxxxxx> CC: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CC: Ingo Molnar <mingo@xxxxxxx> --- kernel/sched.c | 6 ++---- 1 files changed, 2 insertions(+), 4 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index 31f91d9..b046754 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4679,10 +4679,8 @@ void set_user_nice(struct task_struct *p, long nice) goto out_unlock; } on_rq = p->se.on_rq; - if (on_rq) { + if (on_rq) dequeue_task(rq, p, 0); - dec_load(rq, p); - }p->static_prio = NICE_TO_PRIO(nice);set_load_weight(p); @@ -4692,7 +4690,7 @@ void set_user_nice(struct task_struct *p, long nice)if (on_rq) {enqueue_task(rq, p, 0); - inc_load(rq, p); + /* * If the task increased its priority or is running and * lowered its priority, then reschedule its CPU:-- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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