Re: [PATCH] ifb: add multi-queue support

[Patrick McHardy <kaber@trash.net>]

Changli Gao wrote:
> On Tue, Nov 10, 2009 at 8:19 PM, Patrick McHardy <kaber@trash.net> wrote:
>   
>> You have to add a get_tx_queues() callback to the rtnl_link_ops.
>>     
>
> It is used to get the current real_num_tx_queues and num_tx_queues,
> not to setting.
>   

Yes, it gets the number from a user-supplied parameter for device
allocation.

>> Additionally you need a new attribute (IFLA_NTXQ or something like
>> that) that contains the number of queues. The callback has to parse
>> the attribute and set the number of queues accordingly.
>>     
>
> It seems another patch is needed first.
>   

Its a trivial change, you can put them in the same patch:

static int ifb_get_tx_queues(struct net *net, struct nlattr *tb[],
                             unsigned int *num_tx_queues,
                             unsigned int *real_num_tx_queues)
{
    unsigned int n = 1;

    if (tb[IFLA_NTXQ])
       n = nla_get_u32(tb[IFLA_NTXQ]);

    *num_tx_queues = n;
    *real_num_tx_queues = n;
    return 0;
}

>>> Does this work?
>>>
>>>         ifb_link_ops.priv_size = sizeof(struct ifb_private) * numtxqs;
>>>         rtnl_lock();
>>>         err = __rtnl_link_register(&ifb_link_ops);
>>>       
>> Only for the module parameter. For rtnl_link you need to either
>> allocate the private space seperately or turn priv_size into
>> a callback that returns the required space based on the number
>> of queues.
>>     
>
> Do you means that if module ifb is loaded automatically, parameters
> won't be set correctly?

No, I mean if you add a proper interface for this, you have to deal
with different interfaces using a different amount of queues.