RE: [PATCH net-next v2 12/33] hv_netvsc: add XDP frame size to driver

Haiyang Zhang
2020-04-30T14:20:25Z

> -----Original Message-----
> From: Jesper Dangaard Brouer <brouer@redhat.com>
> Sent: Thursday, April 30, 2020 7:21 AM
> To: sameehj@amazon.com
> Cc: Wei Liu <wei.liu@kernel.org>; KY Srinivasan <kys@microsoft.com>;
> Haiyang Zhang <haiyangz@microsoft.com>; Stephen Hemminger
> <sthemmin@microsoft.com>; Jesper Dangaard Brouer
> <brouer@redhat.com>; netdev@vger.kernel.org; bpf@vger.kernel.org;
> zorik@amazon.com; akiyano@amazon.com; gtzalik@amazon.com; Toke
> Høiland-Jørgensen <toke@redhat.com>; Daniel Borkmann
> <borkmann@iogearbox.net>; Alexei Starovoitov
> <alexei.starovoitov@gmail.com>; John Fastabend
> <john.fastabend@gmail.com>; Alexander Duyck
> <alexander.duyck@gmail.com>; Jeff Kirsher <jeffrey.t.kirsher@intel.com>;
> David Ahern <dsahern@gmail.com>; Willem de Bruijn
> <willemdebruijn.kernel@gmail.com>; Ilias Apalodimas
> <ilias.apalodimas@linaro.org>; Lorenzo Bianconi <lorenzo@kernel.org>;
> Saeed Mahameed <saeedm@mellanox.com>;
> steffen.klassert@secunet.com
> Subject: [PATCH net-next v2 12/33] hv_netvsc: add XDP frame size to driver
>
> The hyperv NIC drivers XDP implementation is rather disappointing as it will
> be a slowdown to enable XDP on this driver, given it will allocate a new page
> for each packet and copy over the payload, before invoking the XDP BPF-
> prog.
This needs correction. As I said previously --
This statement is not accurate -- The data path of netvsc driver does memory
allocation and copy even without XDP, so it's not "a slowdown to enable XDP".

Thanks,
- Haiyang