This patch let vhost_net try rx busy polling of underlying net device
when busy polling is enabled. Test shows some improvement on TCP_RR:
smp=1 queue=1
size/session/+thu%/+normalize%/+tpkts%/+rpkts%/+ioexits%/
1/ 1/ +4%/ +3%/ +3%/ +3%/ +22%
1/ 50/ +2%/ +2%/ +2%/ +2%/ 0%
1/ 100/ +1%/ 0%/ +1%/ +1%/ -1%
1/ 200/ +2%/ +1%/ +2%/ +2%/ 0%
64/ 1/ +1%/ +3%/ +1%/ +1%/ +1%
64/ 50/ 0%/ 0%/ 0%/ 0%/ -1%
64/ 100/ +1%/ 0%/ +1%/ +1%/ 0%
64/ 200/ 0%/ 0%/ +2%/ +2%/ 0%
256/ 1/ +2%/ +2%/ +2%/ +2%/ +2%
256/ 50/ +3%/ +3%/ +3%/ +3%/ 0%
256/ 100/ +1%/ +1%/ +2%/ +2%/ 0%
256/ 200/ 0%/ 0%/ +1%/ +1%/ +1%
1024/ 1/ +2%/ +2%/ +2%/ +2%/ +2%
1024/ 50/ -1%/ -1%/ -1%/ -1%/ -2%
1024/ 100/ +1%/ +1%/ 0%/ 0%/ -1%
1024/ 200/ +2%/ +1%/ +2%/ +2%/ 0%
smp=8 queue=1
size/session/+thu%/+normalize%/+tpkts%/+rpkts%/+ioexits%/
1/ 1/ +1%/ -5%/ +1%/ +1%/ 0%
1/ 50/ +1%/ 0%/ +1%/ +1%/ -1%
1/ 100/ -1%/ -1%/ -2%/ -2%/ -4%
1/ 200/ 0%/ 0%/ 0%/ 0%/ -1%
64/ 1/ -2%/ -10%/ -2%/ -2%/ -2%
64/ 50/ -1%/ -1%/ -1%/ -1%/ -2%
64/ 100/ -1%/ 0%/ 0%/ 0%/ -1%
64/ 200/ -1%/ -1%/ 0%/ 0%/ 0%
256/ 1/ +7%/ +25%/ +7%/ +7%/ +7%
256/ 50/ +2%/ +2%/ +2%/ +2%/ -1%
256/ 100/ -1%/ -1%/ -1%/ -1%/ -3%
256/ 200/ +1%/ 0%/ 0%/ 0%/ 0%
1024/ 1/ +5%/ +15%/ +5%/ +5%/ +4%
1024/ 50/ 0%/ 0%/ -1%/ -1%/ -1%
1024/ 100/ -1%/ -1%/ -1%/ -1%/ -2%
1024/ 200/ -1%/ 0%/ -1%/ -1%/ -1%
smp=8 queue=8
size/session/+thu%/+normalize%/+tpkts%/+rpkts%/+ioexits%/
1/ 1/ +5%/ +2%/ +5%/ +5%/ 0%
1/ 50/ +2%/ +2%/ +3%/ +3%/ -20%
1/ 100/ +5%/ +5%/ +5%/ +5%/ -13%
1/ 200/ +8%/ +8%/ +6%/ +6%/ -12%
64/ 1/ 0%/ +4%/ 0%/ 0%/ +18%
64/ 50/ +6%/ +5%/ +5%/ +5%/ -7%
64/ 100/ +4%/ +4%/ +5%/ +5%/ -12%
64/ 200/ +5%/ +5%/ +5%/ +5%/ -12%
256/ 1/ 0%/ -3%/ 0%/ 0%/ +1%
256/ 50/ +3%/ +3%/ +3%/ +3%/ -2%
256/ 100/ +6%/ +5%/ +5%/ +5%/ -11%
256/ 200/ +4%/ +4%/ +4%/ +4%/ -13%
1024/ 1/ 0%/ -3%/ 0%/ 0%/ -6%
1024/ 50/ +1%/ +1%/ +1%/ +1%/ -10%
1024/ 100/ +4%/ +4%/ +5%/ +5%/ -11%
1024/ 200/ +4%/ +5%/ +4%/ +4%/ -12%
Signed-off-by: Jason Wang <jasow...@redhat.com>
---
drivers/vhost/net.c | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index f744eeb..7350f6c 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -27,6 +27,7 @@
#include <linux/if_vlan.h>
#include <net/sock.h>
+#include <net/busy_poll.h>
#include "vhost.h"
@@ -307,15 +308,24 @@ static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
unsigned int *out_num, unsigned int *in_num)
{
unsigned long uninitialized_var(endtime);
+ struct socket *sock = vq->private_data;
+ struct sock *sk = sock->sk;
+ struct napi_struct *napi;
int r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
out_num, in_num, NULL, NULL);
if (r == vq->num && vq->busyloop_timeout) {
preempt_disable();
+ rcu_read_lock();
+ napi = napi_by_id(sk->sk_napi_id);
endtime = busy_clock() + vq->busyloop_timeout;
while (vhost_can_busy_poll(vq->dev, endtime) &&
- vhost_vq_avail_empty(vq->dev, vq))
+ vhost_vq_avail_empty(vq->dev, vq)) {
+ if (napi)
+ sk_busy_loop_once(sk, napi);
cpu_relax_lowlatency();
+ }
+ rcu_read_unlock();
preempt_enable();
r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
out_num, in_num, NULL, NULL);
@@ -476,6 +486,7 @@ static int vhost_net_rx_peek_head_len(struct vhost_net
*net, struct sock *sk)
struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
struct vhost_virtqueue *vq = &nvq->vq;
unsigned long uninitialized_var(endtime);
+ struct napi_struct *napi;
int len = peek_head_len(sk);
if (!len && vq->busyloop_timeout) {
@@ -484,13 +495,20 @@ static int vhost_net_rx_peek_head_len(struct vhost_net
*net, struct sock *sk)
vhost_disable_notify(&net->dev, vq);
preempt_disable();
+ rcu_read_lock();
+
+ napi = napi_by_id(sk->sk_napi_id);
endtime = busy_clock() + vq->busyloop_timeout;
while (vhost_can_busy_poll(&net->dev, endtime) &&
skb_queue_empty(&sk->sk_receive_queue) &&
- vhost_vq_avail_empty(&net->dev, vq))
+ vhost_vq_avail_empty(&net->dev, vq)) {
+ if (napi)
+ sk_busy_loop_once(sk, napi);
cpu_relax_lowlatency();
+ }
+ rcu_read_unlock();
preempt_enable();
if (vhost_enable_notify(&net->dev, vq))
--
2.5.0
