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net/mlx5e: Build SKB in place over the first fragment in non-linear legacy RQ

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As a performance optimization and preparation to enabling XDP multi
buffer on non-linear legacy RQ, build the linear part of the SKB over
the first fragment, instead of allocating a new buffer and copying the
first 256 bytes there.

To achieve this, add headroom and tailroom to the first fragment.

Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
This commit is contained in:
Maxim Mikityanskiy 2022-01-26 17:18:26 +02:00 committed by Saeed Mahameed
parent c3cce0fff3
commit 8d35fb57fd
2 changed files with 57 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

43
drivers/net/ethernet/mellanox/mlx5/core/en/params.c
View File

@ -188,12 +188,18 @@ u16 mlx5e_get_rq_headroom(struct mlx5_core_dev *mdev,
struct mlx5e_params *params,
struct mlx5e_xsk_param *xsk)
{
bool is_linear_skb = (params->rq_wq_type == MLX5_WQ_TYPE_CYCLIC) ?
mlx5e_rx_is_linear_skb(params, xsk) :
mlx5e_rx_mpwqe_is_linear_skb(mdev, params, xsk);
u16 linear_headroom = mlx5e_get_linear_rq_headroom(params, xsk);
return is_linear_skb || params->packet_merge.type == MLX5E_PACKET_MERGE_SHAMPO ?
mlx5e_get_linear_rq_headroom(params, xsk) : 0;
if (params->rq_wq_type == MLX5_WQ_TYPE_CYCLIC)
return linear_headroom;
if (mlx5e_rx_mpwqe_is_linear_skb(mdev, params, xsk))
return linear_headroom;
if (params->packet_merge.type == MLX5E_PACKET_MERGE_SHAMPO)
return linear_headroom;
return 0;
}
u16 mlx5e_calc_sq_stop_room(struct mlx5_core_dev *mdev, struct mlx5e_params *params)
@ -392,10 +398,10 @@ void mlx5e_build_create_cq_param(struct mlx5e_create_cq_param *ccp, struct mlx5e
};
}
static int mlx5e_max_nonlinear_mtu(int frag_size)
static int mlx5e_max_nonlinear_mtu(int first_frag_size, int frag_size)
{
/* Optimization for small packets: the last fragment is bigger than the others. */
return (MLX5E_MAX_RX_FRAGS - 1) * frag_size + PAGE_SIZE;
return first_frag_size + (MLX5E_MAX_RX_FRAGS - 2) * frag_size + PAGE_SIZE;
}
#define DEFAULT_FRAG_SIZE (2048)
@ -407,7 +413,9 @@ static int mlx5e_build_rq_frags_info(struct mlx5_core_dev *mdev,
{
u32 byte_count = MLX5E_SW2HW_MTU(params, params->sw_mtu);
int frag_size_max = DEFAULT_FRAG_SIZE;
int first_frag_size_max;
u32 buf_size = 0;
u16 headroom;
int max_mtu;
int i;
@ -427,11 +435,15 @@ static int mlx5e_build_rq_frags_info(struct mlx5_core_dev *mdev,
goto out;
}
max_mtu = mlx5e_max_nonlinear_mtu(frag_size_max);
headroom = mlx5e_get_linear_rq_headroom(params, xsk);
first_frag_size_max = SKB_WITH_OVERHEAD(frag_size_max - headroom);
max_mtu = mlx5e_max_nonlinear_mtu(first_frag_size_max, frag_size_max);
if (byte_count > max_mtu) {
frag_size_max = PAGE_SIZE;
first_frag_size_max = SKB_WITH_OVERHEAD(frag_size_max - headroom);
max_mtu = mlx5e_max_nonlinear_mtu(frag_size_max);
max_mtu = mlx5e_max_nonlinear_mtu(first_frag_size_max, frag_size_max);
if (byte_count > max_mtu) {
mlx5_core_err(mdev, "MTU %u is too big for non-linear legacy RQ (max %d)\n",
params->sw_mtu, max_mtu);
@ -443,13 +455,22 @@ static int mlx5e_build_rq_frags_info(struct mlx5_core_dev *mdev,
while (buf_size < byte_count) {
int frag_size = byte_count - buf_size;
if (i < MLX5E_MAX_RX_FRAGS - 1)
if (i == 0)
frag_size = min(frag_size, first_frag_size_max);
else if (i < MLX5E_MAX_RX_FRAGS - 1)
frag_size = min(frag_size, frag_size_max);
info->arr[i].frag_size = frag_size;
buf_size += frag_size;
if (i == 0) {
/* Ensure that headroom and tailroom are included. */
frag_size += headroom;
frag_size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
}
info->arr[i].frag_stride = roundup_pow_of_two(frag_size);
buf_size += frag_size;
i++;
}
info->num_frags = i;

48
drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
View File

@ -1560,43 +1560,45 @@ mlx5e_skb_from_cqe_nonlinear(struct mlx5e_rq *rq, struct mlx5_cqe64 *cqe,
struct mlx5e_wqe_frag_info *wi, u32 cqe_bcnt)
{
struct mlx5e_rq_frag_info *frag_info = &rq->wqe.info.arr[0];
struct mlx5e_wqe_frag_info *head_wi = wi;
u16 headlen = min_t(u32, MLX5E_RX_MAX_HEAD, cqe_bcnt);
u16 frag_headlen = headlen;
u16 byte_cnt = cqe_bcnt - headlen;
u16 rx_headroom = rq->buff.headroom;
struct mlx5e_dma_info *di = wi->di;
u32 frag_consumed_bytes;
u32 first_frag_size;
struct sk_buff *skb;
void *va;
va = page_address(di->page) + wi->offset;
frag_consumed_bytes = min_t(u32, frag_info->frag_size, cqe_bcnt);
first_frag_size = MLX5_SKB_FRAG_SZ(rx_headroom + frag_consumed_bytes);
dma_sync_single_range_for_cpu(rq->pdev, di->addr, wi->offset,
first_frag_size, DMA_FROM_DEVICE);
net_prefetch(va + rx_headroom);
/* XDP is not supported in this configuration, as incoming packets
* might spread among multiple pages.
*/
skb = napi_alloc_skb(rq->cq.napi,
ALIGN(MLX5E_RX_MAX_HEAD, sizeof(long)));
if (unlikely(!skb)) {
rq->stats->buff_alloc_err++;
skb = mlx5e_build_linear_skb(rq, va, first_frag_size, rx_headroom,
frag_consumed_bytes, 0);
if (unlikely(!skb))
return NULL;
}
net_prefetchw(skb->data);
page_ref_inc(di->page);
while (byte_cnt) {
u16 frag_consumed_bytes =
min_t(u16, frag_info->frag_size - frag_headlen, byte_cnt);
cqe_bcnt -= frag_consumed_bytes;
frag_info++;
wi++;
mlx5e_add_skb_frag(rq, skb, wi->di, wi->offset + frag_headlen,
while (cqe_bcnt) {
frag_consumed_bytes = min_t(u32, frag_info->frag_size, cqe_bcnt);
mlx5e_add_skb_frag(rq, skb, wi->di, wi->offset,
frag_consumed_bytes, frag_info->frag_stride);
byte_cnt -= frag_consumed_bytes;
frag_headlen = 0;
cqe_bcnt -= frag_consumed_bytes;
frag_info++;
wi++;
}
/* copy header */
mlx5e_copy_skb_header(rq->pdev, skb, head_wi->di, head_wi->offset, head_wi->offset,
headlen);
/* skb linear part was allocated with headlen and aligned to long */
skb->tail += headlen;
skb->len += headlen;
return skb;
}