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rcu: Tighten up affinity and check for sysidle
If the RCU grace-period kthread invoking rcu_sysidle_check_cpu() happens to be running on the tick_do_timer_cpu initially, then rcu_bind_gp_kthread() won't bind it. This kthread might then migrate before invoking rcu_gp_fqs(), which will trigger the WARN_ON_ONCE() in rcu_sysidle_check_cpu(). This commit therefore makes rcu_bind_gp_kthread() do the binding even if the kthread is currently on the same CPU. Because this incurs added overhead, this commit also causes each RCU grace-period kthread to invoke rcu_bind_gp_kthread() once at boot rather than at the beginning of each grace period. And as long as rcu_bind_gp_kthread() is being modified, this commit eliminates its #ifdef. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
parent
675da67f24
commit
5871968d53
2 changed files with 7 additions and 7 deletions
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@ -1707,7 +1707,6 @@ static int rcu_gp_init(struct rcu_state *rsp)
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struct rcu_node *rnp = rcu_get_root(rsp);
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ACCESS_ONCE(rsp->gp_activity) = jiffies;
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rcu_bind_gp_kthread();
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raw_spin_lock_irq(&rnp->lock);
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smp_mb__after_unlock_lock();
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if (!ACCESS_ONCE(rsp->gp_flags)) {
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@ -1895,6 +1894,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
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struct rcu_state *rsp = arg;
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struct rcu_node *rnp = rcu_get_root(rsp);
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rcu_bind_gp_kthread();
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for (;;) {
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/* Handle grace-period start. */
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@ -2763,7 +2763,8 @@ static void rcu_sysidle_exit(int irq)
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/*
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* Check to see if the current CPU is idle. Note that usermode execution
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* does not count as idle. The caller must have disabled interrupts.
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* does not count as idle. The caller must have disabled interrupts,
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* and must be running on tick_do_timer_cpu.
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*/
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static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle,
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unsigned long *maxj)
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@ -2784,8 +2785,8 @@ static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle,
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if (!*isidle || rdp->rsp != rcu_state_p ||
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cpu_is_offline(rdp->cpu) || rdp->cpu == tick_do_timer_cpu)
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return;
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if (rcu_gp_in_progress(rdp->rsp))
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WARN_ON_ONCE(smp_processor_id() != tick_do_timer_cpu);
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/* Verify affinity of current kthread. */
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WARN_ON_ONCE(smp_processor_id() != tick_do_timer_cpu);
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/* Pick up current idle and NMI-nesting counter and check. */
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cur = atomic_read(&rdtp->dynticks_idle);
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@ -3068,11 +3069,10 @@ static void rcu_bind_gp_kthread(void)
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return;
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#ifdef CONFIG_NO_HZ_FULL_SYSIDLE
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cpu = tick_do_timer_cpu;
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if (cpu >= 0 && cpu < nr_cpu_ids && raw_smp_processor_id() != cpu)
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if (cpu >= 0 && cpu < nr_cpu_ids)
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set_cpus_allowed_ptr(current, cpumask_of(cpu));
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#else /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */
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if (!is_housekeeping_cpu(raw_smp_processor_id()))
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housekeeping_affine(current);
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housekeeping_affine(current);
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#endif /* #else #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */
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}
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