On Tue, 21 May 2013, David Miller wrote:
> From: Pekka Riikonen <priik...@iki.fi>
> Date: Tue, 21 May 2013 19:02:19 +0200 (CEST)
>
>> On Tue, 21 May 2013, Eric Dumazet wrote:
>>
>> : > > Alternatively, use a napi_id instead of a pointer.
>> : >
>> : > I'm not sure I understand what you propose.
>> :
>> : Oh well.
>> :
>> : To get a pointer to a struct net_device, we can use ifindex, and do a
>> : rcu lookup into a hash table to get the net_device. We do not need
>> : {pointer,ifindex} but {ifindex} is enough
>> :
>> : My suggestion is to not have skb->skb_ref but skb->napi_index : Its safe
>> : to copy its value from skb->napi_index to sk->napi_index without
>> : refcounting.
>> :
>> : All NAPI need to get a unique napi_index, and be inserted in a hash
>> : table for immediate/fast lookup.
>> :
>> Maybe even that's not needed. Couldn't skb->queue_mapping give the
>> correct NAPI instance in multiqueue nics? The NAPI instance could be made
>> easily available from skb->dev. In any case an index is much better than
>> a new pointer.
>
> Queue mapping is more volatile, and consider layered devices.
>
Yes, true. The napi_index then is probably the way to go. Main thing for
me is that it doesn't increase skb size when in union with dma_cookie (skb
has been growing lately).
Pekka
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