netdev - Re: [PATCH 3/3] ifb: move tq from ifb

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Date:	Sun, 5 Dec 2010 23:16:53 +0800
From:	Changli Gao <xiaosuo@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	hadi@...erus.ca, Jarek Poplawski <jarkao2@...il.com>,
	netdev@...r.kernel.org
Subject: Re: [PATCH 3/3] ifb: move tq from ifb_private

On Sun, Dec 5, 2010 at 11:13 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> Le dimanche 05 décembre 2010 à 22:40 +0800, Changli Gao a écrit :
>> On Sun, Dec 5, 2010 at 10:30 PM, jamal <hadi@...erus.ca> wrote:
>> > On Sun, 2010-12-05 at 09:13 +0800, Changli Gao wrote:
>> >
>> >> BTW: My ultimate goal is making ifb a multi-queue NIC, and the number
>> >> of queues is equal to the number of the possible CPUs.
>> >
>> >
>> > My view is this is going to be tricky because:
>> > - we use tasklets. When we  reschedule we can end up on a differrent
>> > cpu.
>>
>> The tasklets always been scheduled to the current CPU unless it has
>> been schedule already on the other CPU.
>>
>> > -I dont see any point in having a separate softIRQ
>> > - and if you do use other mechanisms it would require a lot more
>> > testing since there are quiet a few use cases of ifb
>> >
>>
>> I keep using tasklet. The attachment is the alpha version.
>>
>
>        for_each_possible_cpu(cpu) {
>                q = per_cpu_ptr(p->q, cpu);
> ...
>
>        dev_ifb = alloc_netdev_mq(sizeof(struct ifb_private), "ifb%d",
>                                  ifb_setup, num_possible_cpus());
>
> This is a very usual error.
>
> You can have machines with 2 possibles cpus, numbered 0 and 8
>
> Therere, you must use nr_cpu_ids here instead of num_possible_cpus()
>

Thanks.


-- 
Regards,
Changli Gao(xiaosuo@...il.com)
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