On Fri, Dec 2, 2016 at 6:36 AM, Edward Cree [off-list ref] wrote:

On 01/12/16 23:46, Tom Herbert wrote:

quoted

The only time we
_really_ to allocate an skbuf is when we need to put the packet onto a
queue. All the other use cases are really just to pass a structure
containing a packet from function to function. For that purpose we
should be able to just pass a much smaller structure in a stack
argument and only allocate an skbuff when we need to enqueue. In cases
where we don't ever queue a packet we might never need to allocate any
skbuff

Now this intrigues me, because one of the objections to bundling (vs GRO)
was the memory usage of all those SKBs.  IIRC we already do a 'GRO-like'
coalescing when packets reach a TCP socket anyway (or at least in some
cases, not sure if all the different ways we can enqueue a TCP packet for
RX do it), but if we could carry the packets from NIC to socket without
SKBs, doing so in lists rather than one-at-a-time wouldn't cost any extra
memory (the packet-pages are all already allocated on the NIC RX ring).
Possibly combine the two, so that rather than having potentially four
versions of each function (skb, skbundle, void*, void* bundle) you just
have the two 'ends'.

Yep, seems like a good idea to incorporate bundling into TXDP from the get-go.

Tom

-Ed