| Date | Wed, 23 Feb 2011 03:44:24 +0100 | From | Frederic Weisbecker <> | Subject | Re: [PATCH RFC tip/core/rcu 11/11] rcu: move TREE_RCU from softirq to kthread |
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On Tue, Feb 22, 2011 at 05:39:40PM -0800, Paul E. McKenney wrote: > +static int rcu_node_kthread(void *arg) > +{ > + int cpu; > + unsigned long flags; > + unsigned long mask; > + struct rcu_node *rnp = (struct rcu_node *)arg; > + struct sched_param sp; > + struct task_struct *t; > + > + for (;;) { > + wait_event_interruptible(rnp->node_wq, rnp->wakemask != 0 || > + kthread_should_stop()); > + if (kthread_should_stop()) > + break; > + raw_spin_lock_irqsave(&rnp->lock, flags); > + mask = rnp->wakemask; > + rnp->wakemask = 0; > + raw_spin_unlock_irqrestore(&rnp->lock, flags); > + for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask <<= 1) {
I may be confused, but shouldn't it be mask >>= 1 instead?
rnp->wakemask is the unioned rdp->grpmask of the cpu(s) for which we woke that node thread up. Those mask start from 0, so what you want with the below check is to watch if the next CPU in group range is in the wakeup mask by shifting to the right.
No?
> + if ((mask & 0x1) == 0) > + continue; > + preempt_disable(); > + per_cpu(rcu_cpu_has_work, cpu) = 1; > + t = per_cpu(rcu_cpu_kthread_task, cpu); > + if (t == NULL) { > + preempt_enable(); > + continue; > + } > + sp.sched_priority = RCU_KTHREAD_PRIO; > + sched_setscheduler_nocheck(t, cpu, &sp); > + wake_up_process(t); > + preempt_enable(); > + } > + } > + return 0; > +}
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