net/mlx4_en: add xdp forwarding and data write support
A user will now be able to loop packets back out of the same port using a bpf program attached to xdp hook. Updates to the packet contents from the bpf program is also supported. For the packet write feature to work, the rx buffers are now mapped as bidirectional when the page is allocated. This occurs only when the xdp hook is active. When the program returns a TX action, enqueue the packet directly to a dedicated tx ring, so as to avoid completely any locking. This requires the tx ring to be allocated 1:1 for each rx ring, as well as the tx completion running in the same softirq. Upon tx completion, this dedicated tx ring recycles pages without unmapping directly back to the original rx ring. In steady state tx/drop workload, effectively 0 page allocs/frees will occur. In order to separate out the paths between free and recycle, a free_tx_desc func pointer is introduced that is optionally updated whenever recycle_ring is activated. By default the original free function is always initialized. Signed-off-by:Brenden Blanco <bblanco@plumgrid.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
parent
224e92e0
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