On Thu, May 31, 2018 at 2:00 AM, Jesper Dangaard Brouer <bro...@redhat.com> wrote: > This is the first real user of the XDP_XMIT_FLUSH flag. > > As pointed out many times, XDP_REDIRECT without using BPF maps is > significant slower than the map variant. This is primary due to the > lack of bulking, as the ndo_xdp_flush operation is required after each > frame (to avoid frames hanging on the egress device). > > It is still possible to optimize this case. Instead of invoking two > NDO indirect calls, which are very expensive with CONFIG_RETPOLINE, > instead instruct ndo_xdp_xmit to flush via XDP_XMIT_FLUSH flag. > > Signed-off-by: Jesper Dangaard Brouer <bro...@redhat.com>
Acked-by: Song Liu <songliubrav...@fb.com> > --- > net/core/filter.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/net/core/filter.c b/net/core/filter.c > index 6a21dbcad350..6981b4608979 100644 > --- a/net/core/filter.c > +++ b/net/core/filter.c > @@ -3056,10 +3056,9 @@ static int __bpf_tx_xdp(struct net_device *dev, > if (unlikely(!xdpf)) > return -EOVERFLOW; > > - sent = dev->netdev_ops->ndo_xdp_xmit(dev, 1, &xdpf, 0); > + sent = dev->netdev_ops->ndo_xdp_xmit(dev, 1, &xdpf, XDP_XMIT_FLUSH); > if (sent <= 0) > return sent; > - dev->netdev_ops->ndo_xdp_flush(dev); > return 0; > } > >
