>>> On Fri, Jul 18, 2008 at 8:39 AM, in message <1216384754.28405.31.camel@twins>, Peter Zijlstra <peterz@xxxxxxxxxxxxx> 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. Perhaps I was trying to hit a moving target, or did not have enough coffee that day ;) I will look again to see if I made a mistake. Thanks Peter, -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 -- 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
