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>
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@ -6788,6 +6788,11 @@ out_unlock:
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return 0;
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}
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static inline int on_null_domain(struct rq *rq)
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{
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return unlikely(!rcu_dereference_sched(rq->sd));
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}
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#ifdef CONFIG_NO_HZ_COMMON
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/*
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* idle load balancing details
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@ -6842,8 +6847,13 @@ static void nohz_balancer_kick(void)
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static inline void nohz_balance_exit_idle(int cpu)
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{
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if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
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/*
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* Completely isolated CPUs don't ever set, so we must test.
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*/
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if (likely(cpumask_test_cpu(cpu, nohz.idle_cpus_mask))) {
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cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
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atomic_dec(&nohz.nr_cpus);
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}
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clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
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}
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}
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@ -6897,6 +6907,12 @@ void nohz_balance_enter_idle(int cpu)
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if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
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return;
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/*
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* If we're a completely isolated CPU, we don't play.
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*/
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if (on_null_domain(cpu_rq(cpu)))
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return;
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cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
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atomic_inc(&nohz.nr_cpus);
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set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
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@ -7159,11 +7175,6 @@ static void run_rebalance_domains(struct softirq_action *h)
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nohz_idle_balance(this_rq, idle);
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}
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static inline int on_null_domain(struct rq *rq)
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{
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return !rcu_dereference_sched(rq->sd);
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}
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/*
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* Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
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*/
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