On 2020-04-08 14:52, Jesper Dangaard Brouer wrote:
The mlx5 driver have multiple memory models, which are also changed
according to whether a XDP bpf_prog is attached.
The 'rx_striding_rq' setting is adjusted via ethtool priv-flags e.g.:
# ethtool --set-priv-flags mlx5p2 rx_striding_rq off
On the general case with 4K page_size and regular MTU packet, then
the frame_sz is 2048 and 4096 when XDP is enabled, in both modes.
The info on the given frame size is stored differently depending on the
RQ-mode and encoded in a union in struct mlx5e_rq union wqe/mpwqe.
In rx striding mode rq->mpwqe.log_stride_sz is either 11 or 12, which
corresponds to 2048 or 4096 (MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ).
In non-striding mode (MLX5_WQ_TYPE_CYCLIC) the frag_stride is stored
in rq->wqe.info.arr[0].frag_stride.
To reduce effect on fast-path, this patch determine the frame_sz at
setup time, to avoid determining the memory model runtime.
Cc: Tariq Toukan <tariqt@xxxxxxxxxxxx>
Cc: Saeed Mahameed <saeedm@xxxxxxxxxxxx>
Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
---
drivers/net/ethernet/mellanox/mlx5/core/en.h | 1 +
drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c | 1 +
drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 4 ++++
3 files changed, 6 insertions(+)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
index 12a61bf82c14..1f280fc142ca 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
@@ -651,6 +651,7 @@ struct mlx5e_rq {
struct {
u16 umem_headroom;
u16 headroom;
+ u32 frame_sz;
u8 map_dir; /* dma map direction */
} buff;
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
index f049e0ac308a..de4ad2c9f49a 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
@@ -137,6 +137,7 @@ bool mlx5e_xdp_handle(struct mlx5e_rq *rq, struct mlx5e_dma_info *di,
if (xsk)
xdp.handle = di->xsk.handle;
xdp.rxq = &rq->xdp_rxq;
+ xdp.frame_sz = rq->buff.frame_sz;
act = bpf_prog_run_xdp(prog, &xdp);
if (xsk) {
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index dd7f338425eb..b9595315c45b 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -462,6 +462,8 @@ static int mlx5e_alloc_rq(struct mlx5e_channel *c,
rq->mpwqe.num_strides =
BIT(mlx5e_mpwqe_get_log_num_strides(mdev, params, xsk));
+ rq->buff.frame_sz = (1 << rq->mpwqe.log_stride_sz);
I think it won't be correct from AF_XDP perspective in case unaligned
chunks are in use. As I see by the patches for Intel's drivers,
xdp.frame_sz is set to chunk_size_nohr + headroom, which is not always a
power of two.
Moreover, it won't be correct for standard (aligned to a power of two)
chunks either, because mlx5e_rx_get_linear_frag_sz always rounds up to
PAGE_SIZE in case of XDP (this usage of striding RQ is somewhat hackish
when it comes to AF_XDP), so we will end up with frame_sz == PAGE_SIZE.
So, I think we just need to use `xsk->chunk_size` here for frame_sz. The
same for non-striding RQ.
+
err = mlx5e_create_rq_umr_mkey(mdev, rq);
if (err)
goto err_rq_wq_destroy;
@@ -485,6 +487,8 @@ static int mlx5e_alloc_rq(struct mlx5e_channel *c,
num_xsk_frames = wq_sz << rq->wqe.info.log_num_frags;
rq->wqe.info = rqp->frags_info;
+ rq->buff.frame_sz = rq->wqe.info.arr[0].frag_stride;
+
rq->wqe.frags =
kvzalloc_node(array_size(sizeof(*rq->wqe.frags),
(wq_sz << rq->wqe.info.log_num_frags)),
