net/mlx4_en: add page recycle to prepare rx ring for tx support
The mlx4 driver by default allocates order-3 pages for the ring to
consume in multiple fragments. When the device has an xdp program, this
behavior will prevent tx actions since the page must be re-mapped in
TODEVICE mode, which cannot be done if the page is still shared.
Start by making the allocator configurable based on whether xdp is
running, such that order-0 pages are always used and never shared.
Since this will stress the page allocator, add a simple page cache to
each rx ring. Pages in the cache are left dma-mapped, and in drop-only
stress tests the page allocator is eliminated from the perf report.
Note that setting an xdp program will now require the rings to be
reconfigured.
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>