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sched, nohz: Exclude isolated cores from load balancing 

The user explicitly disabled load balancing, else this core would not be
disconnected.  Don't add these to nohz.idle_cpus_mask.

Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Lei Wen <leiwen@marvell.com>
Link: http://lkml.kernel.org/n/tip-vmme4f49psirp966pklm5l9j@git.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
hifive-unleashed-5.1
Mike Galbraith 2011-12-05 10:01:47 +01:00 committed by Ingo Molnar
parent de91b9cb97
commit d987fc7f32
1 changed files with 18 additions and 7 deletions
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25
kernel/sched/fair.c
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@ -6788,6 +6788,11 @@ out_unlock:
return 0;
}
static inline int on_null_domain(struct rq *rq)
{
return unlikely(!rcu_dereference_sched(rq->sd));
}
#ifdef CONFIG_NO_HZ_COMMON
/*
* idle load balancing details
@ -6842,8 +6847,13 @@ static void nohz_balancer_kick(void)
static inline void nohz_balance_exit_idle(int cpu)
{
if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
atomic_dec(&nohz.nr_cpus);
/*
* Completely isolated CPUs don't ever set, so we must test.
*/
if (likely(cpumask_test_cpu(cpu, nohz.idle_cpus_mask))) {
cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
atomic_dec(&nohz.nr_cpus);
}
clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
}
}
@ -6897,6 +6907,12 @@ void nohz_balance_enter_idle(int cpu)
if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
return;
/*
* If we're a completely isolated CPU, we don't play.
*/
if (on_null_domain(cpu_rq(cpu)))
return;
cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
atomic_inc(&nohz.nr_cpus);
set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
@ -7159,11 +7175,6 @@ static void run_rebalance_domains(struct softirq_action *h)
nohz_idle_balance(this_rq, idle);
}
static inline int on_null_domain(struct rq *rq)
{
return !rcu_dereference_sched(rq->sd);
}
/*
* Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
*/