networking benchmark shows that __rcu_read_lock and
__rcu_read_unlock takes some cpu cycles, and we can avoid
calling them partially in virtio rx path by check xdp_enabled
of vi, and xdp is disabled most of time
Signed-off-by: Li RongQing <lirongqing@xxxxxxxxx>
---
drivers/net/virtio_net.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 2ed49884565f..74d2be438180 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -734,6 +734,12 @@ static struct sk_buff *receive_small(struct net_device *dev,
dev->stats.rx_length_errors++;
goto err_len;
}
+
+ if (likely(!vi->xdp_enabled)) {
+ xdp_prog = NULL;
+ goto skip_xdp;
+ }
+
rcu_read_lock();
xdp_prog = rcu_dereference(rq->xdp_prog);
if (xdp_prog) {
@@ -816,6 +822,7 @@ static struct sk_buff *receive_small(struct net_device *dev,
}
rcu_read_unlock();
+skip_xdp:
skb = build_skb(buf, buflen);
if (!skb) {
put_page(page);
@@ -897,6 +904,12 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
dev->stats.rx_length_errors++;
goto err_skb;
}
+
+ if (likely(!vi->xdp_enabled)) {
+ xdp_prog = NULL;
+ goto skip_xdp;
+ }
+
rcu_read_lock();
xdp_prog = rcu_dereference(rq->xdp_prog);
if (xdp_prog) {
@@ -1024,6 +1037,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
}
rcu_read_unlock();
+skip_xdp:
head_skb = page_to_skb(vi, rq, page, offset, len, truesize, !xdp_prog,
metasize, headroom);
curr_skb = head_skb;
--
2.33.0.69.gc420321.dirty
