mbox series

[v2,0/9] virtio_net: support multi buffer xdp

Message ID 20221220141449.115918-1-hengqi@linux.alibaba.com (mailing list archive)
Headers show
Series virtio_net: support multi buffer xdp | expand

Message

Heng Qi Dec. 20, 2022, 2:14 p.m. UTC
Changes since RFC:
- Using headroom instead of vi->xdp_enabled to avoid re-reading
  in add_recvbuf_mergeable();
- Disable GRO_HW and keep linearization for single buffer xdp;
- Renamed to virtnet_build_xdp_buff_mrg();
- pr_debug() to netdev_dbg();
- Adjusted the order of the patch series.

Currently, virtio net only supports xdp for single-buffer packets
or linearized multi-buffer packets. This patchset supports xdp for
multi-buffer packets, then larger MTU can be used if xdp sets the
xdp.frags. This does not affect single buffer handling.

In order to build multi-buffer xdp neatly, we integrated the code
into virtnet_build_xdp_buff_mrg() for xdp. The first buffer is used
for prepared xdp buff, and the rest of the buffers are added to
its skb_shared_info structure. This structure can also be
conveniently converted during XDP_PASS to get the corresponding skb.

Since virtio net uses comp pages, and bpf_xdp_frags_increase_tail()
is based on the assumption of the page pool,
(rxq->frag_size - skb_frag_size(frag) - skb_frag_off(frag))
is negative in most cases. So we didn't set xdp_rxq->frag_size in
virtnet_open() to disable the tail increase.

Heng Qi (9):
  virtio_net: disable the hole mechanism for xdp
  virtio_net: set up xdp for multi buffer packets
  virtio_net: update bytes calculation for xdp_frame
  virtio_net: build xdp_buff with multi buffers
  virtio_net: construct multi-buffer xdp in mergeable
  virtio_net: transmit the multi-buffer xdp
  virtio_net: build skb from multi-buffer xdp
  virtio_net: remove xdp related info from page_to_skb()
  virtio_net: support multi-buffer xdp

 drivers/net/virtio_net.c | 332 ++++++++++++++++++++++++++-------------
 1 file changed, 219 insertions(+), 113 deletions(-)

Comments

Jakub Kicinski Dec. 22, 2022, 1:30 a.m. UTC | #1
On Tue, 20 Dec 2022 22:14:40 +0800 Heng Qi wrote:
> Changes since RFC:
> - Using headroom instead of vi->xdp_enabled to avoid re-reading
>   in add_recvbuf_mergeable();
> - Disable GRO_HW and keep linearization for single buffer xdp;
> - Renamed to virtnet_build_xdp_buff_mrg();
> - pr_debug() to netdev_dbg();
> - Adjusted the order of the patch series.

# Form letter - net-next is closed

We have already submitted the networking pull request to Linus
for v6.2 and therefore net-next is closed for new drivers, features,
code refactoring and optimizations. We are currently accepting
bug fixes only.

Please repost when net-next reopens after Jan 2nd.

RFC patches sent for review only are obviously welcome at any time.
Heng Qi Dec. 22, 2022, 2:04 a.m. UTC | #2
在 2022/12/22 上午9:30, Jakub Kicinski 写道:
> On Tue, 20 Dec 2022 22:14:40 +0800 Heng Qi wrote:
>> Changes since RFC:
>> - Using headroom instead of vi->xdp_enabled to avoid re-reading
>>    in add_recvbuf_mergeable();
>> - Disable GRO_HW and keep linearization for single buffer xdp;
>> - Renamed to virtnet_build_xdp_buff_mrg();
>> - pr_debug() to netdev_dbg();
>> - Adjusted the order of the patch series.
> # Form letter - net-next is closed
>
> We have already submitted the networking pull request to Linus
> for v6.2 and therefore net-next is closed for new drivers, features,
> code refactoring and optimizations. We are currently accepting
> bug fixes only.
>
> Please repost when net-next reopens after Jan 2nd.
>
> RFC patches sent for review only are obviously welcome at any time.

Yes, I understand, we can also review this patch series first.

Thanks.
Heng Qi Dec. 26, 2022, 2:32 a.m. UTC | #3
Hi Jason, do you have any comments on this?

Thanks.

在 2022/12/20 下午10:14, Heng Qi 写道:
> Changes since RFC:
> - Using headroom instead of vi->xdp_enabled to avoid re-reading
>    in add_recvbuf_mergeable();
> - Disable GRO_HW and keep linearization for single buffer xdp;
> - Renamed to virtnet_build_xdp_buff_mrg();
> - pr_debug() to netdev_dbg();
> - Adjusted the order of the patch series.
>
> Currently, virtio net only supports xdp for single-buffer packets
> or linearized multi-buffer packets. This patchset supports xdp for
> multi-buffer packets, then larger MTU can be used if xdp sets the
> xdp.frags. This does not affect single buffer handling.
>
> In order to build multi-buffer xdp neatly, we integrated the code
> into virtnet_build_xdp_buff_mrg() for xdp. The first buffer is used
> for prepared xdp buff, and the rest of the buffers are added to
> its skb_shared_info structure. This structure can also be
> conveniently converted during XDP_PASS to get the corresponding skb.
>
> Since virtio net uses comp pages, and bpf_xdp_frags_increase_tail()
> is based on the assumption of the page pool,
> (rxq->frag_size - skb_frag_size(frag) - skb_frag_off(frag))
> is negative in most cases. So we didn't set xdp_rxq->frag_size in
> virtnet_open() to disable the tail increase.
>
> Heng Qi (9):
>    virtio_net: disable the hole mechanism for xdp
>    virtio_net: set up xdp for multi buffer packets
>    virtio_net: update bytes calculation for xdp_frame
>    virtio_net: build xdp_buff with multi buffers
>    virtio_net: construct multi-buffer xdp in mergeable
>    virtio_net: transmit the multi-buffer xdp
>    virtio_net: build skb from multi-buffer xdp
>    virtio_net: remove xdp related info from page_to_skb()
>    virtio_net: support multi-buffer xdp
>
>   drivers/net/virtio_net.c | 332 ++++++++++++++++++++++++++-------------
>   1 file changed, 219 insertions(+), 113 deletions(-)
>
Jason Wang Dec. 26, 2022, 4:14 a.m. UTC | #4
On Mon, Dec 26, 2022 at 10:33 AM Heng Qi <hengqi@linux.alibaba.com> wrote:
>
>
> Hi Jason, do you have any comments on this?

I will review this no later than the end of this week.

Thanks

>
> Thanks.
>
> 在 2022/12/20 下午10:14, Heng Qi 写道:
> > Changes since RFC:
> > - Using headroom instead of vi->xdp_enabled to avoid re-reading
> >    in add_recvbuf_mergeable();
> > - Disable GRO_HW and keep linearization for single buffer xdp;
> > - Renamed to virtnet_build_xdp_buff_mrg();
> > - pr_debug() to netdev_dbg();
> > - Adjusted the order of the patch series.
> >
> > Currently, virtio net only supports xdp for single-buffer packets
> > or linearized multi-buffer packets. This patchset supports xdp for
> > multi-buffer packets, then larger MTU can be used if xdp sets the
> > xdp.frags. This does not affect single buffer handling.
> >
> > In order to build multi-buffer xdp neatly, we integrated the code
> > into virtnet_build_xdp_buff_mrg() for xdp. The first buffer is used
> > for prepared xdp buff, and the rest of the buffers are added to
> > its skb_shared_info structure. This structure can also be
> > conveniently converted during XDP_PASS to get the corresponding skb.
> >
> > Since virtio net uses comp pages, and bpf_xdp_frags_increase_tail()
> > is based on the assumption of the page pool,
> > (rxq->frag_size - skb_frag_size(frag) - skb_frag_off(frag))
> > is negative in most cases. So we didn't set xdp_rxq->frag_size in
> > virtnet_open() to disable the tail increase.
> >
> > Heng Qi (9):
> >    virtio_net: disable the hole mechanism for xdp
> >    virtio_net: set up xdp for multi buffer packets
> >    virtio_net: update bytes calculation for xdp_frame
> >    virtio_net: build xdp_buff with multi buffers
> >    virtio_net: construct multi-buffer xdp in mergeable
> >    virtio_net: transmit the multi-buffer xdp
> >    virtio_net: build skb from multi-buffer xdp
> >    virtio_net: remove xdp related info from page_to_skb()
> >    virtio_net: support multi-buffer xdp
> >
> >   drivers/net/virtio_net.c | 332 ++++++++++++++++++++++++++-------------
> >   1 file changed, 219 insertions(+), 113 deletions(-)
> >
>