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Date: Fri, 15 Jul 2016 03:46:31 -0400
From: Jason Wang <jasowang@...hat.com>
To: davem@...emloft.net, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: mst@...hat.com, Jason Wang <jasowang@...hat.com>
Subject: [PATCH net-next 2/2] 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 <jasowang@...hat.com>
---
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 <net/rtnetlink.h>
#include <net/sock.h>
#include <linux/virtio_net.h>
+#include <linux/skb_array.h>
/*
* 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;
--
1.8.3.1
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