[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Re: SKB paged fragment lifecycle on receive
On Fri, 2011-06-24 at 13:11 -0700, Jeremy Fitzhardinge wrote: > On 06/24/2011 12:46 PM, David Miller wrote: > > Pages get transferred between different SKBs all the time. > > > > For example, GRO makes extensive use of this technique. > > See net/core/skbuff.c:skb_gro_receive(). > > > > It is just one example. > > I see, and the new skb doesn't get a destructor copied from the > original, so there'd be no second callback. What about if we were to have a per-shinfo destructor (called once for each page as its refcount goes 1->0, from whichever skb ends up with the last ref) as well as the skb-destructors. This already handles the cloning case but when pages are moved between shinfo then would it make sense for that to be propagated between skb's under these circumstances and/or require them to be the same? Since in the case of something like skb_gro_receive the skbs (and hence the frag array pages) are all from the same 'owner' (even if the skb is actually created by the stack on their behalf) I suspect this could work? But I bet this assumption isn't valid in all cases. In which case I end up wondering about a destructor per page in the frag array. At which point we might as well consider it as a part of the core mm stuff rather than something net specific? Ian. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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