diff options
author | Jesper Dangaard Brouer <brouer@redhat.com> | 2018-04-17 16:46:32 +0200 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2018-04-17 10:50:29 -0400 |
commit | 039930945a72d9af5ff04ae9b9e60658a52e0770 (patch) | |
tree | e92821099697576bcdcd41e9d61f561be0e6923c /drivers | |
parent | 60bbf7eeef10dc647430646d7fe5e3d8d132dbec (diff) | |
download | op-kernel-dev-039930945a72d9af5ff04ae9b9e60658a52e0770.zip op-kernel-dev-039930945a72d9af5ff04ae9b9e60658a52e0770.tar.gz |
xdp: transition into using xdp_frame for return API
Changing API xdp_return_frame() to take struct xdp_frame as argument,
seems like a natural choice. But there are some subtle performance
details here that needs extra care, which is a deliberate choice.
When de-referencing xdp_frame on a remote CPU during DMA-TX
completion, result in the cache-line is change to "Shared"
state. Later when the page is reused for RX, then this xdp_frame
cache-line is written, which change the state to "Modified".
This situation already happens (naturally) for, virtio_net, tun and
cpumap as the xdp_frame pointer is the queued object. In tun and
cpumap, the ptr_ring is used for efficiently transferring cache-lines
(with pointers) between CPUs. Thus, the only option is to
de-referencing xdp_frame.
It is only the ixgbe driver that had an optimization, in which it can
avoid doing the de-reference of xdp_frame. The driver already have
TX-ring queue, which (in case of remote DMA-TX completion) have to be
transferred between CPUs anyhow. In this data area, we stored a
struct xdp_mem_info and a data pointer, which allowed us to avoid
de-referencing xdp_frame.
To compensate for this, a prefetchw is used for telling the cache
coherency protocol about our access pattern. My benchmarks show that
this prefetchw is enough to compensate the ixgbe driver.
V7: Adjust for commit d9314c474d4f ("i40e: add support for XDP_REDIRECT")
V8: Adjust for commit bd658dda4237 ("net/mlx5e: Separate dma base address
and offset in dma_sync call")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/net/ethernet/intel/i40e/i40e_txrx.c | 5 | ||||
-rw-r--r-- | drivers/net/ethernet/intel/ixgbe/ixgbe.h | 4 | ||||
-rw-r--r-- | drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 17 | ||||
-rw-r--r-- | drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 1 | ||||
-rw-r--r-- | drivers/net/tun.c | 4 | ||||
-rw-r--r-- | drivers/net/virtio_net.c | 2 |
6 files changed, 18 insertions, 15 deletions
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c index 96c54cb..c8bf4d3 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c @@ -638,8 +638,7 @@ static void i40e_unmap_and_free_tx_resource(struct i40e_ring *ring, if (tx_buffer->tx_flags & I40E_TX_FLAGS_FD_SB) kfree(tx_buffer->raw_buf); else if (ring_is_xdp(ring)) - xdp_return_frame(tx_buffer->xdpf->data, - &tx_buffer->xdpf->mem); + xdp_return_frame(tx_buffer->xdpf); else dev_kfree_skb_any(tx_buffer->skb); if (dma_unmap_len(tx_buffer, len)) @@ -842,7 +841,7 @@ static bool i40e_clean_tx_irq(struct i40e_vsi *vsi, /* free the skb/XDP data */ if (ring_is_xdp(tx_ring)) - xdp_return_frame(tx_buf->xdpf->data, &tx_buf->xdpf->mem); + xdp_return_frame(tx_buf->xdpf); else napi_consume_skb(tx_buf->skb, napi_budget); diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h index abb5248..7dd5038 100644 --- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h @@ -241,8 +241,7 @@ struct ixgbe_tx_buffer { unsigned long time_stamp; union { struct sk_buff *skb; - /* XDP uses address ptr on irq_clean */ - void *data; + struct xdp_frame *xdpf; }; unsigned int bytecount; unsigned short gso_segs; @@ -250,7 +249,6 @@ struct ixgbe_tx_buffer { DEFINE_DMA_UNMAP_ADDR(dma); DEFINE_DMA_UNMAP_LEN(len); u32 tx_flags; - struct xdp_mem_info xdp_mem; }; struct ixgbe_rx_buffer { diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c index f10904e..4f28641 100644 --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c @@ -1216,7 +1216,7 @@ static bool ixgbe_clean_tx_irq(struct ixgbe_q_vector *q_vector, /* free the skb */ if (ring_is_xdp(tx_ring)) - xdp_return_frame(tx_buffer->data, &tx_buffer->xdp_mem); + xdp_return_frame(tx_buffer->xdpf); else napi_consume_skb(tx_buffer->skb, napi_budget); @@ -2386,6 +2386,7 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector, xdp.data_hard_start = xdp.data - ixgbe_rx_offset(rx_ring); xdp.data_end = xdp.data + size; + prefetchw(xdp.data_hard_start); /* xdp_frame write */ skb = ixgbe_run_xdp(adapter, rx_ring, &xdp); } @@ -5797,7 +5798,7 @@ static void ixgbe_clean_tx_ring(struct ixgbe_ring *tx_ring) /* Free all the Tx ring sk_buffs */ if (ring_is_xdp(tx_ring)) - xdp_return_frame(tx_buffer->data, &tx_buffer->xdp_mem); + xdp_return_frame(tx_buffer->xdpf); else dev_kfree_skb_any(tx_buffer->skb); @@ -8348,16 +8349,21 @@ static int ixgbe_xmit_xdp_ring(struct ixgbe_adapter *adapter, struct ixgbe_ring *ring = adapter->xdp_ring[smp_processor_id()]; struct ixgbe_tx_buffer *tx_buffer; union ixgbe_adv_tx_desc *tx_desc; + struct xdp_frame *xdpf; u32 len, cmd_type; dma_addr_t dma; u16 i; - len = xdp->data_end - xdp->data; + xdpf = convert_to_xdp_frame(xdp); + if (unlikely(!xdpf)) + return -EOVERFLOW; + + len = xdpf->len; if (unlikely(!ixgbe_desc_unused(ring))) return IXGBE_XDP_CONSUMED; - dma = dma_map_single(ring->dev, xdp->data, len, DMA_TO_DEVICE); + dma = dma_map_single(ring->dev, xdpf->data, len, DMA_TO_DEVICE); if (dma_mapping_error(ring->dev, dma)) return IXGBE_XDP_CONSUMED; @@ -8372,8 +8378,7 @@ static int ixgbe_xmit_xdp_ring(struct ixgbe_adapter *adapter, dma_unmap_len_set(tx_buffer, len, len); dma_unmap_addr_set(tx_buffer, dma, dma); - tx_buffer->data = xdp->data; - tx_buffer->xdp_mem = xdp->rxq->mem; + tx_buffer->xdpf = xdpf; tx_desc->read.buffer_addr = cpu_to_le64(dma); diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c index f42436d..7bbf0db 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c @@ -890,6 +890,7 @@ struct sk_buff *skb_from_cqe(struct mlx5e_rq *rq, struct mlx5_cqe64 *cqe, dma_sync_single_range_for_cpu(rq->pdev, di->addr, wi->offset, frag_size, DMA_FROM_DEVICE); + prefetchw(va); /* xdp_frame data area */ prefetch(data); wi->offset += frag_size; diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 283bde8..bec130c 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -663,7 +663,7 @@ void tun_ptr_free(void *ptr) if (tun_is_xdp_frame(ptr)) { struct xdp_frame *xdpf = tun_ptr_to_xdp(ptr); - xdp_return_frame(xdpf->data, &xdpf->mem); + xdp_return_frame(xdpf); } else { __skb_array_destroy_skb(ptr); } @@ -2196,7 +2196,7 @@ static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile, struct xdp_frame *xdpf = tun_ptr_to_xdp(ptr); ret = tun_put_user_xdp(tun, tfile, xdpf, to); - xdp_return_frame(xdpf->data, &xdpf->mem); + xdp_return_frame(xdpf); } else { struct sk_buff *skb = ptr; diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 42d338f..ab3d7cb 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -430,7 +430,7 @@ static int __virtnet_xdp_xmit(struct virtnet_info *vi, /* Free up any pending old buffers before queueing new ones. */ while ((xdpf_sent = virtqueue_get_buf(sq->vq, &len)) != NULL) - xdp_return_frame(xdpf_sent->data, &xdpf_sent->mem); + xdp_return_frame(xdpf_sent); xdpf = convert_to_xdp_frame(xdp); if (unlikely(!xdpf)) |