netdev - Re: [RFC] rps: shortcut net_rps

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <p2u412e6f7f1004190528l65cc6253w8b7f43f2657b551d@mail.gmail.com>
Date:	Mon, 19 Apr 2010 20:28:27 +0800
From:	Changli Gao <xiaosuo@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Tom Herbert <therbert@...gle.com>,
	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>
Subject: Re: [RFC] rps: shortcut net_rps_action()

On Mon, Apr 19, 2010 at 8:14 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
>
> 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@...il.com)
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html