On 2014/2/12 13:28, Jason Wang wrote:
A question: without NAPI weight, could this starve other net devices?
tap xmit skb use thread context，the poll func of physical nic driver
could be called in softirq context without change.
I had test it by binding vhost thread and physic nic interrupt on the
same vcpu, use netperf xmit udp, test model is VM1-Host1-Host2.
if only VM1 xmit skb, the top show as below :
Cpu1 :0.0%us, 95.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 5.0%si, 0.0%st
then use host2 xmit skb to VM1, the top show as below :
Cpu1 :0.0%us, 41.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 59.0%si, 0.0%st
so I think there is no problem with this change.
drivers/net/tun.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 44c4db8..90b4e58 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1184,7 +1184,9 @@ static ssize_t tun_get_user(struct tun_struct
*tun, struct tun_file *tfile,
skb_probe_transport_header(skb, 0);
rxhash = skb_get_hash(skb);
- netif_rx_ni(skb);
+ rcu_read_lock_bh();
+ netif_receive_skb(skb);
+ rcu_read_unlock_bh();
tun->dev->stats.rx_packets++;
tun->dev->stats.rx_bytes += len;
.
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