On Thu, 2018-03-29 at 19:02 +0200, Jesper Dangaard Brouer wrote: > This patch shows how it is possible to have both the driver local > page > cache, which uses elevated refcnt for "catching"/avoiding SKB > put_page returns the page through the page allocator. And at the > same time, have pages getting returned to the page_pool from > ndp_xdp_xmit DMA completion. > > The performance improvement for XDP_REDIRECT in this patch is really > good. Especially considering that (currently) the xdp_return_frame > API and page_pool_put_page() does per frame operations of both > rhashtable ID-lookup and locked return into (page_pool) ptr_ring. > (It is the plan to remove these per frame operation in a followup > patchset). > > The benchmark performed was RX on mlx5 and XDP_REDIRECT out ixgbe, > with xdp_redirect_map (using devmap) . And the target/maximum > capability of ixgbe is 13Mpps (on this HW setup). > > Before this patch for mlx5, XDP redirected frames were returned via > the page allocator. The single flow performance was 6Mpps, and if I > started two flows the collective performance drop to 4Mpps, because > we > hit the page allocator lock (further negative scaling occurs). > > Two test scenarios need to be covered, for xdp_return_frame API, > which > is DMA-TX completion running on same-CPU or cross-CPU free/return. > Results were same-CPU=10Mpps, and cross-CPU=12Mpps. This is very > close to our 13Mpps max target. > > The reason max target isn't reached in cross-CPU test, is likely due > to RX-ring DMA unmap/map overhead (which doesn't occur in ixgbe to > ixgbe testing). It is also planned to remove this unnecessary DMA > unmap in a later patchset > > V2: Adjustments requested by Tariq > - Changed page_pool_create return codes not return NULL, only > ERR_PTR, as this simplifies err handling in drivers. > - Save a branch in mlx5e_page_release > - Correct page_pool size calc for > MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ > > V5: Updated patch desc > > Signed-off-by: Jesper Dangaard Brouer <bro...@redhat.com> > Reviewed-by: Tariq Toukan <tar...@mellanox.com>
Acked-by: Saeed Mahameed <sae...@mellanox.com>
