On Tue, 24 Feb 2015 13:39:46 -0500
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> +static void tell_cpu_to_push(int cpu, struct rq *rq, int prio)
> +{
> + /* We should never be here if the IPI is already out. */
> + BUG_ON(rq->rt.push_csd_pending);
> +
> + rq->rt.push_csd_pending = 1;
> + rq->rt.push_csd_cpu = cpu;
> + /* Save the prio that we used to find this CPU */
> + rq->rt.push_csd_prio = prio;
> +
> + /* Make sure csd_cpu is visible before we send the ipi */
> + smp_mb();
> +
> + smp_call_function_single_async(cpu, &rq->rt.push_csd);
> +}
> + rt_rq->push_csd_cpu = next_cpu;
> + rt_rq->push_csd_prio = next_prio;
> +
> + /* Make sure the next cpu is seen on remote CPU */
> + smp_mb();
BTW, would a smp_wmb() be enough here. I was a little paranoid about
the irq work and smp_call_functon above some how leaking before the
barrier. I'm probably just being too paranoid, and these can be
switched to smp_wmb(). But for now I'll just keep being a freak.
-- Steve
> +
> + irq_work_queue_on(&rt_rq->push_csd_work, next_cpu);
> +
> + return;
> +
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