[PATCH][net-next] virtio_net: skip RCU read lock by checking xdp_enabled of vi
From: Li RongQing <hidden>
Date: 2021-10-09 09:41:00
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 <redacted> --- 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