On 2018/11/7 下午5:34, Paolo Abeni wrote:
The tun XDP sendmsg code path, unconditionally computes the symmetric hash of each packet for RFS's sake, even when we could skip it. e.g. when the device has a single queue. This change adds the check already in-place for the skb sendmsg path to avoid unneeded hashing. The above gives small, but measurable, performance gain for VM xmit path when zerocopy is not enabled. Signed-off-by: Paolo Abeni <pab...@redhat.com> --- drivers/net/tun.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 060135ceaf0e..a65779c6d72f 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -2448,7 +2448,8 @@ static int tun_xdp_one(struct tun_struct *tun, goto out; }- if (!rcu_dereference(tun->steering_prog))+ if (!rcu_dereference(tun->steering_prog) && tun->numqueues > 1 && + !tfile->detached) rxhash = __skb_get_hash_symmetric(skb);netif_receive_skb(skb);
Acked-by: Jason Wang <jasow...@redhat.com> Thanks
