xdp: change ndo_xdp_xmit API to support bulking
This patch change the API for ndo_xdp_xmit to support bulking xdp_frames. When kernel is compiled with CONFIG_RETPOLINE, XDP sees a huge slowdown. Most of the slowdown is caused by DMA API indirect function calls, but also the net_device->ndo_xdp_xmit() call. Benchmarked patch with CONFIG_RETPOLINE, using xdp_redirect_map with single flow/core test (CPU E5-1650 v4 @ 3.60GHz), showed performance improved: for driver ixgbe: 6,042,682 pps -> 6,853,768 pps = +811,086 pps for driver i40e : 6,187,169 pps -> 6,724,519 pps = +537,350 pps With frames avail as a bulk inside the driver ndo_xdp_xmit call, further optimizations are possible, like bulk DMA-mapping for TX. Testing without CONFIG_RETPOLINE show the same performance for physical NIC drivers. The virtual NIC driver tun sees a huge performance boost, as it can avoid doing per frame producer locking, but instead amortize the locking cost over the bulk. V2: Fix compile errors reported by kbuild test robot <lkp@intel.com> V4: Isolated ndo, driver changes and callers. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
parent
389ab7f01a
commit
735fc4054b
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@ -3664,14 +3664,19 @@ netdev_tx_t i40e_lan_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
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* @dev: netdev
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* @xdp: XDP buffer
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*
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* Returns Zero if sent, else an error code
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* Returns number of frames successfully sent. Frames that fail are
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* free'ed via XDP return API.
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*
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* For error cases, a negative errno code is returned and no-frames
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* are transmitted (caller must handle freeing frames).
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**/
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int i40e_xdp_xmit(struct net_device *dev, struct xdp_frame *xdpf)
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int i40e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames)
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{
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struct i40e_netdev_priv *np = netdev_priv(dev);
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unsigned int queue_index = smp_processor_id();
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struct i40e_vsi *vsi = np->vsi;
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int err;
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int drops = 0;
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int i;
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if (test_bit(__I40E_VSI_DOWN, vsi->state))
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return -ENETDOWN;
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@ -3679,11 +3684,18 @@ int i40e_xdp_xmit(struct net_device *dev, struct xdp_frame *xdpf)
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if (!i40e_enabled_xdp_vsi(vsi) || queue_index >= vsi->num_queue_pairs)
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return -ENXIO;
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err = i40e_xmit_xdp_ring(xdpf, vsi->xdp_rings[queue_index]);
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if (err != I40E_XDP_TX)
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return -ENOSPC;
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for (i = 0; i < n; i++) {
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struct xdp_frame *xdpf = frames[i];
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int err;
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return 0;
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err = i40e_xmit_xdp_ring(xdpf, vsi->xdp_rings[queue_index]);
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if (err != I40E_XDP_TX) {
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xdp_return_frame_rx_napi(xdpf);
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drops++;
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}
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}
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return n - drops;
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}
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/**
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@ -487,7 +487,7 @@ u32 i40e_get_tx_pending(struct i40e_ring *ring, bool in_sw);
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void i40e_detect_recover_hung(struct i40e_vsi *vsi);
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int __i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size);
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bool __i40e_chk_linearize(struct sk_buff *skb);
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int i40e_xdp_xmit(struct net_device *dev, struct xdp_frame *xdpf);
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int i40e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames);
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void i40e_xdp_flush(struct net_device *dev);
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/**
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@ -10017,11 +10017,13 @@ static int ixgbe_xdp(struct net_device *dev, struct netdev_bpf *xdp)
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}
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}
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static int ixgbe_xdp_xmit(struct net_device *dev, struct xdp_frame *xdpf)
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static int ixgbe_xdp_xmit(struct net_device *dev, int n,
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struct xdp_frame **frames)
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{
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struct ixgbe_adapter *adapter = netdev_priv(dev);
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struct ixgbe_ring *ring;
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int err;
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int drops = 0;
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int i;
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if (unlikely(test_bit(__IXGBE_DOWN, &adapter->state)))
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return -ENETDOWN;
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@ -10033,11 +10035,18 @@ static int ixgbe_xdp_xmit(struct net_device *dev, struct xdp_frame *xdpf)
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if (unlikely(!ring))
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return -ENXIO;
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err = ixgbe_xmit_xdp_ring(adapter, xdpf);
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if (err != IXGBE_XDP_TX)
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return -ENOSPC;
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for (i = 0; i < n; i++) {
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struct xdp_frame *xdpf = frames[i];
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int err;
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return 0;
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err = ixgbe_xmit_xdp_ring(adapter, xdpf);
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if (err != IXGBE_XDP_TX) {
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xdp_return_frame_rx_napi(xdpf);
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drops++;
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}
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}
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return n - drops;
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}
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static void ixgbe_xdp_flush(struct net_device *dev)
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@ -70,6 +70,7 @@
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#include <net/netns/generic.h>
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#include <net/rtnetlink.h>
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#include <net/sock.h>
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#include <net/xdp.h>
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#include <linux/seq_file.h>
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#include <linux/uio.h>
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#include <linux/skb_array.h>
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@ -1290,34 +1291,44 @@ static const struct net_device_ops tun_netdev_ops = {
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.ndo_get_stats64 = tun_net_get_stats64,
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};
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static int tun_xdp_xmit(struct net_device *dev, struct xdp_frame *frame)
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static int tun_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames)
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{
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struct tun_struct *tun = netdev_priv(dev);
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struct tun_file *tfile;
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u32 numqueues;
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int ret = 0;
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int drops = 0;
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int cnt = n;
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int i;
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rcu_read_lock();
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numqueues = READ_ONCE(tun->numqueues);
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if (!numqueues) {
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ret = -ENOSPC;
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goto out;
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rcu_read_unlock();
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return -ENXIO; /* Caller will free/return all frames */
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}
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tfile = rcu_dereference(tun->tfiles[smp_processor_id() %
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numqueues]);
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spin_lock(&tfile->tx_ring.producer_lock);
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for (i = 0; i < n; i++) {
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struct xdp_frame *xdp = frames[i];
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/* Encode the XDP flag into lowest bit for consumer to differ
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* XDP buffer from sk_buff.
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*/
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if (ptr_ring_produce(&tfile->tx_ring, tun_xdp_to_ptr(frame))) {
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this_cpu_inc(tun->pcpu_stats->tx_dropped);
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ret = -ENOSPC;
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}
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void *frame = tun_xdp_to_ptr(xdp);
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if (__ptr_ring_produce(&tfile->tx_ring, frame)) {
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this_cpu_inc(tun->pcpu_stats->tx_dropped);
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xdp_return_frame_rx_napi(xdp);
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drops++;
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}
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}
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spin_unlock(&tfile->tx_ring.producer_lock);
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out:
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rcu_read_unlock();
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return ret;
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return cnt - drops;
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}
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static int tun_xdp_tx(struct net_device *dev, struct xdp_buff *xdp)
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@ -1327,7 +1338,7 @@ static int tun_xdp_tx(struct net_device *dev, struct xdp_buff *xdp)
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if (unlikely(!frame))
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return -EOVERFLOW;
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return tun_xdp_xmit(dev, frame);
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return tun_xdp_xmit(dev, 1, &frame);
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}
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static void tun_xdp_flush(struct net_device *dev)
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@ -419,23 +419,13 @@ static void virtnet_xdp_flush(struct net_device *dev)
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virtqueue_kick(sq->vq);
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}
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static int __virtnet_xdp_xmit(struct virtnet_info *vi,
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static int __virtnet_xdp_xmit_one(struct virtnet_info *vi,
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struct send_queue *sq,
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struct xdp_frame *xdpf)
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{
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struct virtio_net_hdr_mrg_rxbuf *hdr;
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struct xdp_frame *xdpf_sent;
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struct send_queue *sq;
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unsigned int len;
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unsigned int qp;
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int err;
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qp = vi->curr_queue_pairs - vi->xdp_queue_pairs + smp_processor_id();
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sq = &vi->sq[qp];
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/* Free up any pending old buffers before queueing new ones. */
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while ((xdpf_sent = virtqueue_get_buf(sq->vq, &len)) != NULL)
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xdp_return_frame(xdpf_sent);
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/* virtqueue want to use data area in-front of packet */
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if (unlikely(xdpf->metasize > 0))
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return -EOPNOTSUPP;
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@ -459,11 +449,40 @@ static int __virtnet_xdp_xmit(struct virtnet_info *vi,
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return 0;
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}
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static int virtnet_xdp_xmit(struct net_device *dev, struct xdp_frame *xdpf)
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static int __virtnet_xdp_tx_xmit(struct virtnet_info *vi,
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struct xdp_frame *xdpf)
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{
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struct xdp_frame *xdpf_sent;
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struct send_queue *sq;
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unsigned int len;
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unsigned int qp;
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qp = vi->curr_queue_pairs - vi->xdp_queue_pairs + smp_processor_id();
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sq = &vi->sq[qp];
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/* Free up any pending old buffers before queueing new ones. */
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while ((xdpf_sent = virtqueue_get_buf(sq->vq, &len)) != NULL)
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xdp_return_frame(xdpf_sent);
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return __virtnet_xdp_xmit_one(vi, sq, xdpf);
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}
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static int virtnet_xdp_xmit(struct net_device *dev,
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int n, struct xdp_frame **frames)
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{
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struct virtnet_info *vi = netdev_priv(dev);
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struct receive_queue *rq = vi->rq;
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struct xdp_frame *xdpf_sent;
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struct bpf_prog *xdp_prog;
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struct send_queue *sq;
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unsigned int len;
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unsigned int qp;
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int drops = 0;
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int err;
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int i;
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qp = vi->curr_queue_pairs - vi->xdp_queue_pairs + smp_processor_id();
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sq = &vi->sq[qp];
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/* Only allow ndo_xdp_xmit if XDP is loaded on dev, as this
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* indicate XDP resources have been successfully allocated.
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@ -472,7 +491,20 @@ static int virtnet_xdp_xmit(struct net_device *dev, struct xdp_frame *xdpf)
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if (!xdp_prog)
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return -ENXIO;
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return __virtnet_xdp_xmit(vi, xdpf);
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/* Free up any pending old buffers before queueing new ones. */
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while ((xdpf_sent = virtqueue_get_buf(sq->vq, &len)) != NULL)
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xdp_return_frame(xdpf_sent);
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for (i = 0; i < n; i++) {
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struct xdp_frame *xdpf = frames[i];
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err = __virtnet_xdp_xmit_one(vi, sq, xdpf);
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if (err) {
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xdp_return_frame_rx_napi(xdpf);
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drops++;
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}
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}
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return n - drops;
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}
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static unsigned int virtnet_get_headroom(struct virtnet_info *vi)
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@ -616,7 +648,7 @@ static struct sk_buff *receive_small(struct net_device *dev,
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xdpf = convert_to_xdp_frame(&xdp);
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if (unlikely(!xdpf))
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goto err_xdp;
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err = __virtnet_xdp_xmit(vi, xdpf);
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err = __virtnet_xdp_tx_xmit(vi, xdpf);
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if (unlikely(err)) {
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trace_xdp_exception(vi->dev, xdp_prog, act);
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goto err_xdp;
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@ -779,7 +811,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
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xdpf = convert_to_xdp_frame(&xdp);
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if (unlikely(!xdpf))
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goto err_xdp;
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err = __virtnet_xdp_xmit(vi, xdpf);
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err = __virtnet_xdp_tx_xmit(vi, xdpf);
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if (unlikely(err)) {
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trace_xdp_exception(vi->dev, xdp_prog, act);
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if (unlikely(xdp_page != page))
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@ -1185,9 +1185,13 @@ struct dev_ifalias {
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* This function is used to set or query state related to XDP on the
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* netdevice and manage BPF offload. See definition of
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* enum bpf_netdev_command for details.
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* int (*ndo_xdp_xmit)(struct net_device *dev, struct xdp_frame *xdp);
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* This function is used to submit a XDP packet for transmit on a
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* netdevice.
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* int (*ndo_xdp_xmit)(struct net_device *dev, int n, struct xdp_frame **xdp);
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* This function is used to submit @n XDP packets for transmit on a
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* netdevice. Returns number of frames successfully transmitted, frames
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* that got dropped are freed/returned via xdp_return_frame().
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* Returns negative number, means general error invoking ndo, meaning
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* no frames were xmit'ed and core-caller will free all frames.
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* TODO: Consider add flag to allow sending flush operation.
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* void (*ndo_xdp_flush)(struct net_device *dev);
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* This function is used to inform the driver to flush a particular
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* xdp tx queue. Must be called on same CPU as xdp_xmit.
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@ -1375,8 +1379,8 @@ struct net_device_ops {
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int needed_headroom);
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int (*ndo_bpf)(struct net_device *dev,
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struct netdev_bpf *bpf);
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int (*ndo_xdp_xmit)(struct net_device *dev,
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struct xdp_frame *xdp);
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int (*ndo_xdp_xmit)(struct net_device *dev, int n,
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struct xdp_frame **xdp);
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void (*ndo_xdp_flush)(struct net_device *dev);
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};
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@ -232,24 +232,31 @@ static int bq_xmit_all(struct bpf_dtab_netdev *obj,
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prefetch(xdpf);
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}
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for (i = 0; i < bq->count; i++) {
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struct xdp_frame *xdpf = bq->q[i];
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int err;
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err = dev->netdev_ops->ndo_xdp_xmit(dev, xdpf);
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if (err) {
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drops++;
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xdp_return_frame_rx_napi(xdpf);
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} else {
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sent++;
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}
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sent = dev->netdev_ops->ndo_xdp_xmit(dev, bq->count, bq->q);
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if (sent < 0) {
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sent = 0;
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goto error;
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}
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drops = bq->count - sent;
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out:
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bq->count = 0;
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trace_xdp_devmap_xmit(&obj->dtab->map, obj->bit,
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sent, drops, bq->dev_rx, dev);
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bq->dev_rx = NULL;
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return 0;
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error:
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/* If ndo_xdp_xmit fails with an errno, no frames have been
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* xmit'ed and it's our responsibility to them free all.
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*/
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for (i = 0; i < bq->count; i++) {
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struct xdp_frame *xdpf = bq->q[i];
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/* RX path under NAPI protection, can return frames faster */
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xdp_return_frame_rx_napi(xdpf);
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drops++;
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}
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goto out;
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}
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/* __dev_map_flush is called from xdp_do_flush_map() which _must_ be signaled
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@ -3039,7 +3039,7 @@ static int __bpf_tx_xdp(struct net_device *dev,
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u32 index)
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{
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struct xdp_frame *xdpf;
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int err;
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int sent;
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if (!dev->netdev_ops->ndo_xdp_xmit) {
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return -EOPNOTSUPP;
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@ -3049,9 +3049,9 @@ static int __bpf_tx_xdp(struct net_device *dev,
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if (unlikely(!xdpf))
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return -EOVERFLOW;
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err = dev->netdev_ops->ndo_xdp_xmit(dev, xdpf);
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if (err)
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return err;
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sent = dev->netdev_ops->ndo_xdp_xmit(dev, 1, &xdpf);
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if (sent <= 0)
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return sent;
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dev->netdev_ops->ndo_xdp_flush(dev);
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return 0;
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}
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