Re: [Xen-devel] [PATCH] xen/netfront: handle compound page fragments on transmit

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2012-11-20 at 14:45 +0000, Eric Dumazet wrote:
> > +           /* Skip unused frames from start of page */
> 
> 'frame' in the comment means an order-0 page ?

Yes. Confusing in the context of a network driver I know! I couldn't
think of a better term.

> > +                   id = get_id_from_freelist(&np->tx_skb_freelist, 
> > np->tx_skbs);
> > +                   np->tx_skbs[id].skb = skb_get(skb);
> 
> BTW this skb_get() means extra atomic operations for every 4096 bytes
> unit, and an extra atomic op (and test for final 0) at TX completion.
> This could be avoided, by setting np->tx_skbs[id].skb = skb only for the
> very last unit.

Thanks. Might be tricky because guests can ack the individual requests
in any order but it's something worth having a look at.

> >     np->tx.req_prod_pvt = prod;
> 
> Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> 
> Thanks !

Thanks for the review.

Ian.

> 
> 



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