From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [RFC] rps: shortcut net_rps_action()
Date: Mon, 19 Apr 2010 15:27:07 +0200
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Cc: Tom Herbert <therbert@google.com>,
	David Miller <davem@davemloft.net>,
	netdev <netdev@vger.kernel.org>
To: Changli Gao <xiaosuo@gmail.com>
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Le lundi 19 avril 2010 =C3=A0 20:28 +0800, Changli Gao a =C3=A9crit :
> On Mon, Apr 19, 2010 at 8:14 PM, Eric Dumazet <eric.dumazet@gmail.com=
> wrote:
> >
> > As several packets can be enqueued for a given cpu, we would need t=
o
> > 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++] =3D cpu;
> > }
>=20
>         rps_lock(queue);
>         if (queue->input_pkt_queue.qlen <=3D netdev_max_backlog) {
>                 if (queue->input_pkt_queue.qlen) {
> ...
>                 if (napi_schedule_prep(&queue->backlog)) {
> #ifdef CONFIG_RPS
>                         if (cpu !=3D smp_processor_id()) {
>                                 struct rps_remote_softirq_cpus *rcpus=
 =3D
>                                     &__get_cpu_var(rps_remote_softirq=
_cpus);
>=20
>                                 cpu_set(cpu, rcpus->mask[rcpus->selec=
t]);
>                                 __raise_softirq_irqoff(NET_RX_SOFTIRQ=
);
>                                 goto enqueue;
>                         }
> #endif
>                         __napi_schedule(&queue->backlog);
>                 }
>=20
> Only the first packet of a softnet.input_pkt_queue may trigger IPI, s=
o
> we don't need to keep bitmasks.
>=20

This is not true Changli

Please read again all previous mails about RPS, or the code.