Overall, this set looks good to me. The only suggestion I have is to add more
documentation on the expected behavior of XDP_XMIT_FLUSH in netdevice.h
(as part of 01/08).
Thanks,
Song
On Wed, May 30, 2018 at 11:00 AM, Jesper Dangaard Brouer
<bro...@redhat.com> wrote:
> As I mentioned in merge commit 10f678683e4 ("Merge branch 'xdp_xmit-bulking'")
> I plan to change the API for ndo_xdp_xmit once more, by adding a flags
> argument, which is done in this patchset.
>
> I know it is late in the cycle (currently at rc7), but it would be
> nice to avoid changing NDOs over several kernel releases, as it is
> annoying to vendors and distro backporters, but it is not strictly
> UAPI so it is allowed (according to Alexei).
>
> The end-goal is getting rid of the ndo_xdp_flush operation, as it will
> make it possible for drivers to implement a TXQ synchronization mechanism
> that is not necessarily derived from the CPU id (smp_processor_id).
>
> This patchset removes all callers of the ndo_xdp_flush operation, but
> it doesn't take the last step of removing it from all drivers. This
> can be done later, or I can update the patchset on request.
>
> Micro-benchmarks only show a very small performance improvement, for
> map-redirect around ~2 ns, and for non-map redirect ~7 ns. I've not
> benchmarked this with CONFIG_RETPOLINE, but the performance benefit
> should be more visible given we end-up removing an indirect call.
>
> ---
>
> Jesper Dangaard Brouer (8):
> xdp: add flags argument to ndo_xdp_xmit API
> i40e: implement flush flag for ndo_xdp_xmit
> ixgbe: implement flush flag for ndo_xdp_xmit
> tun: implement flush flag for ndo_xdp_xmit
> virtio_net: implement flush flag for ndo_xdp_xmit
> xdp: done implementing ndo_xdp_xmit flush flag for all drivers
> bpf/xdp: non-map redirect can avoid calling ndo_xdp_flush
> bpf/xdp: devmap can avoid calling ndo_xdp_flush
>
>
> drivers/net/ethernet/intel/i40e/i40e_txrx.c | 9 ++++++++-
> drivers/net/ethernet/intel/i40e/i40e_txrx.h | 3 ++-
> drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 23 +++++++++++++++++------
> drivers/net/tun.c | 25
> ++++++++++++++++++-------
> drivers/net/virtio_net.c | 9 ++++++++-
> include/linux/netdevice.h | 7 ++++---
> include/net/xdp.h | 4 ++++
> kernel/bpf/devmap.c | 20 +++++++-------------
> net/core/filter.c | 3 +--
> 9 files changed, 69 insertions(+), 34 deletions(-)
>
> --
