Messages in this thread | | | From | Vincent Guittot <> | Date | Tue, 6 Oct 2020 14:46:28 +0200 | Subject | Re: [PATCH -v2 07/17] sched: Fix hotplug vs CPU bandwidth control |
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On Mon, 5 Oct 2020 at 17:09, Peter Zijlstra <peterz@infradead.org> wrote: > > Since we now migrate tasks away before DYING, we should also move > bandwidth unthrottle, otherwise we can gain tasks from unthrottle > after we expect all tasks to be gone already. > > Also; it looks like the RT balancers don't respect cpu_active() and > instead rely on rq->online in part, complete this. This too requires > we do set_rq_offline() earlier to match the cpu_active() semantics. > (The bigger patch is to convert RT to cpu_active() entirely) > > Since set_rq_online() is called from sched_cpu_activate(), place > set_rq_offline() in sched_cpu_deactivate(). > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > --- > kernel/sched/core.c | 14 ++++++++++---- > kernel/sched/deadline.c | 5 +---- > kernel/sched/rt.c | 5 +---- > 3 files changed, 12 insertions(+), 12 deletions(-) > > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -6979,6 +6979,8 @@ int sched_cpu_activate(unsigned int cpu) > > int sched_cpu_deactivate(unsigned int cpu) > { > + struct rq *rq = cpu_rq(cpu); > + struct rq_flags rf; > int ret; > > set_cpu_active(cpu, false); > @@ -6993,6 +6995,14 @@ int sched_cpu_deactivate(unsigned int cp > > balance_push_set(cpu, true); > > + rq_lock_irqsave(rq, &rf); > + if (rq->rd) { > + update_rq_clock();
Tried to compile but rq parameter is missing
> + BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); > + set_rq_offline(rq); > + } > + rq_unlock_irqrestore(rq, &rf); > + > #ifdef CONFIG_SCHED_SMT > /* > * When going down, decrement the number of cores with SMT present. > @@ -7074,10 +7084,6 @@ int sched_cpu_dying(unsigned int cpu) > sched_tick_stop(cpu); > > rq_lock_irqsave(rq, &rf); > - if (rq->rd) { > - BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); > - set_rq_offline(rq); > - } > BUG_ON(rq->nr_running != 1); > rq_unlock_irqrestore(rq, &rf); > > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -543,7 +543,7 @@ static int push_dl_task(struct rq *rq); > > static inline bool need_pull_dl_task(struct rq *rq, struct task_struct *prev) > { > - return dl_task(prev); > + return rq->online && dl_task(prev); > } > > static DEFINE_PER_CPU(struct callback_head, dl_push_head); > @@ -2326,9 +2326,6 @@ static void rq_online_dl(struct rq *rq) > /* Assumes rq->lock is held */ > static void rq_offline_dl(struct rq *rq) > { > - if (rq->dl.overloaded) > - dl_clear_overload(rq); > - > cpudl_clear(&rq->rd->cpudl, rq->cpu); > cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu); > } > --- a/kernel/sched/rt.c > +++ b/kernel/sched/rt.c > @@ -265,7 +265,7 @@ static void pull_rt_task(struct rq *this > static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev) > { > /* Try to pull RT tasks here if we lower this rq's prio */ > - return rq->rt.highest_prio.curr > prev->prio; > + return rq->online && rq->rt.highest_prio.curr > prev->prio; > } > > static inline int rt_overloaded(struct rq *rq) > @@ -2245,9 +2245,6 @@ static void rq_online_rt(struct rq *rq) > /* Assumes rq->lock is held */ > static void rq_offline_rt(struct rq *rq) > { > - if (rq->rt.overloaded) > - rt_clear_overload(rq); > - > __disable_runtime(rq); > > cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID); > >
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