On Mon, Apr 19, 2010 at 8:14 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
quoted text
>
> As several packets can be enqueued for a given cpu, we would need to
> keep bitmasks.
> We would have to add one test in enqueue_to_backlog()
>
> if (cpu_test_and_set(cpu, mask)) {
>        __raise_softirq_irqoff(NET_RX_SOFTIRQ);
>        array[nb++] = cpu;
> }

        rps_lock(queue);
        if (queue->input_pkt_queue.qlen <= netdev_max_backlog) {
                if (queue->input_pkt_queue.qlen) {
...
                if (napi_schedule_prep(&queue->backlog)) {
#ifdef CONFIG_RPS
                        if (cpu != smp_processor_id()) {
                                struct rps_remote_softirq_cpus *rcpus =
                                    &__get_cpu_var(rps_remote_softirq_cpus);

                                cpu_set(cpu, rcpus->mask[rcpus->select]);
                                __raise_softirq_irqoff(NET_RX_SOFTIRQ);
                                goto enqueue;
                        }
#endif
                        __napi_schedule(&queue->backlog);
                }

Only the first packet of a softnet.input_pkt_queue may trigger IPI, so
we don't need to keep bitmasks.

-- 
Regards，
Changli Gao(xiaosuo@gmail.com)
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html