From 362899b8725b35e32802882c67f99cbf42bce2af Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Fri, 15 Jul 2016 03:46:31 -0400 Subject: [PATCH] macvtap: switch to use skb array This patch switch to use skb array instead of sk_receive_queue to avoid spinlock contentions. Tests shows about 21% improvements for guest rx pps: Before: 1472731 pkts/s After: 1786289 pkts/s Signed-off-by: Jason Wang Signed-off-by: David S. Miller --- drivers/net/macvtap.c | 82 ++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 71 insertions(+), 11 deletions(-) diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index 2476923..9204d19 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -21,6 +21,7 @@ #include #include #include +#include /* * A macvtap queue is the central object of this driver, it connects @@ -43,6 +44,7 @@ struct macvtap_queue { u16 queue_index; bool enabled; struct list_head next; + struct skb_array skb_array; }; #define MACVTAP_FEATURES (IFF_VNET_HDR | IFF_MULTI_QUEUE) @@ -273,6 +275,7 @@ static void macvtap_put_queue(struct macvtap_queue *q) rtnl_unlock(); synchronize_rcu(); + skb_array_cleanup(&q->skb_array); sock_put(&q->sk); } @@ -366,7 +369,7 @@ static rx_handler_result_t macvtap_handle_frame(struct sk_buff **pskb) if (!q) return RX_HANDLER_PASS; - if (skb_queue_len(&q->sk.sk_receive_queue) >= dev->tx_queue_len) + if (__skb_array_full(&q->skb_array)) goto drop; skb_push(skb, ETH_HLEN); @@ -384,7 +387,8 @@ static rx_handler_result_t macvtap_handle_frame(struct sk_buff **pskb) goto drop; if (!segs) { - skb_queue_tail(&q->sk.sk_receive_queue, skb); + if (skb_array_produce(&q->skb_array, skb)) + goto drop; goto wake_up; } @@ -393,7 +397,11 @@ static rx_handler_result_t macvtap_handle_frame(struct sk_buff **pskb) struct sk_buff *nskb = segs->next; segs->next = NULL; - skb_queue_tail(&q->sk.sk_receive_queue, segs); + if (skb_array_produce(&q->skb_array, segs)) { + kfree_skb(segs); + kfree_skb_list(nskb); + break; + } segs = nskb; } } else { @@ -406,7 +414,8 @@ static rx_handler_result_t macvtap_handle_frame(struct sk_buff **pskb) !(features & NETIF_F_CSUM_MASK) && skb_checksum_help(skb)) goto drop; - skb_queue_tail(&q->sk.sk_receive_queue, skb); + if (skb_array_produce(&q->skb_array, skb)) + goto drop; } wake_up: @@ -523,7 +532,11 @@ static void macvtap_sock_write_space(struct sock *sk) static void macvtap_sock_destruct(struct sock *sk) { - skb_queue_purge(&sk->sk_receive_queue); + struct macvtap_queue *q = container_of(sk, struct macvtap_queue, sk); + struct sk_buff *skb; + + while ((skb = skb_array_consume(&q->skb_array)) != NULL) + kfree(skb); } static int macvtap_open(struct inode *inode, struct file *file) @@ -536,13 +549,13 @@ static int macvtap_open(struct inode *inode, struct file *file) rtnl_lock(); dev = dev_get_by_macvtap_minor(iminor(inode)); if (!dev) - goto out; + goto err; err = -ENOMEM; q = (struct macvtap_queue *)sk_alloc(net, AF_UNSPEC, GFP_KERNEL, &macvtap_proto, 0); if (!q) - goto out; + goto err; RCU_INIT_POINTER(q->sock.wq, &q->wq); init_waitqueue_head(&q->wq.wait); @@ -566,11 +579,24 @@ static int macvtap_open(struct inode *inode, struct file *file) if ((dev->features & NETIF_F_HIGHDMA) && (dev->features & NETIF_F_SG)) sock_set_flag(&q->sk, SOCK_ZEROCOPY); + err = -ENOMEM; + if (skb_array_init(&q->skb_array, dev->tx_queue_len, GFP_KERNEL)) + goto err_array; + err = macvtap_set_queue(dev, file, q); if (err) - sock_put(&q->sk); + goto err_queue; -out: + dev_put(dev); + + rtnl_unlock(); + return err; + +err_queue: + skb_array_cleanup(&q->skb_array); +err_array: + sock_put(&q->sk); +err: if (dev) dev_put(dev); @@ -596,7 +622,7 @@ static unsigned int macvtap_poll(struct file *file, poll_table * wait) mask = 0; poll_wait(file, &q->wq.wait, wait); - if (!skb_queue_empty(&q->sk.sk_receive_queue)) + if (!skb_array_empty(&q->skb_array)) mask |= POLLIN | POLLRDNORM; if (sock_writeable(&q->sk) || @@ -856,7 +882,7 @@ static ssize_t macvtap_do_read(struct macvtap_queue *q, TASK_INTERRUPTIBLE); /* Read frames from the queue */ - skb = skb_dequeue(&q->sk.sk_receive_queue); + skb = skb_array_consume(&q->skb_array); if (skb) break; if (noblock) { @@ -1180,10 +1206,18 @@ static int macvtap_recvmsg(struct socket *sock, struct msghdr *m, return ret; } +static int macvtap_peek_len(struct socket *sock) +{ + struct macvtap_queue *q = container_of(sock, struct macvtap_queue, + sock); + return skb_array_peek_len(&q->skb_array); +} + /* Ops structure to mimic raw sockets with tun */ static const struct proto_ops macvtap_socket_ops = { .sendmsg = macvtap_sendmsg, .recvmsg = macvtap_recvmsg, + .peek_len = macvtap_peek_len, }; /* Get an underlying socket object from tun file. Returns error unless file is @@ -1202,6 +1236,28 @@ struct socket *macvtap_get_socket(struct file *file) } EXPORT_SYMBOL_GPL(macvtap_get_socket); +static int macvtap_queue_resize(struct macvlan_dev *vlan) +{ + struct net_device *dev = vlan->dev; + struct macvtap_queue *q; + struct skb_array **arrays; + int n = vlan->numqueues; + int ret, i = 0; + + arrays = kmalloc(sizeof *arrays * n, GFP_KERNEL); + if (!arrays) + return -ENOMEM; + + list_for_each_entry(q, &vlan->queue_list, next) + arrays[i++] = &q->skb_array; + + ret = skb_array_resize_multiple(arrays, n, + dev->tx_queue_len, GFP_KERNEL); + + kfree(arrays); + return ret; +} + static int macvtap_device_event(struct notifier_block *unused, unsigned long event, void *ptr) { @@ -1249,6 +1305,10 @@ static int macvtap_device_event(struct notifier_block *unused, device_destroy(&macvtap_class, devt); macvtap_free_minor(vlan); break; + case NETDEV_CHANGE_TX_QUEUE_LEN: + if (macvtap_queue_resize(vlan)) + return NOTIFY_BAD; + break; } return NOTIFY_DONE; -- 2.7.4