Re: [PATCH net-next] virtio-net: switch to use build_skb() for small buffer

From	Jason Wang <jasowang@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH net-next] virtio-net: switch to use build_skb() for small buffer
Date	2017-02-22 04:20 +0100
Message-ID	<tdvDc-3G6-5@gated-at.bofh.it> (permalink)
References	<tdeiZ-6w-1@gated-at.bofh.it> <tdjLI-3P2-15@gated-at.bofh.it> <tdvjQ-3cX-5@gated-at.bofh.it> <tdvtw-3w9-5@gated-at.bofh.it>
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On 2017年02月22日 11:06, Michael S. Tsirkin wrote:
> On Wed, Feb 22, 2017 at 10:58:08AM +0800, Jason Wang wrote:
>>
>> On 2017年02月21日 22:37, Michael S. Tsirkin wrote:
>>> On Tue, Feb 21, 2017 at 04:46:28PM +0800, Jason Wang wrote:
>>>> This patch switch to use build_skb() for small buffer which can have
>>>> better performance for both TCP and XDP (since we can work at page
>>>> before skb creation). It also remove lots of XDP codes since both
>>>> mergeable and small buffer use page frag during refill now.
>>>>
>>>>                          Before   | After
>>>> XDP_DROP(xdp1) 64B  :  11.1Mpps | 14.4Mpps
>>>>
>>>> Tested with xdp1/xdp2/xdp_ip_tx_tunnel and netperf.
>>>>
>>>> Signed-off-by: Jason Wang<jasowang@redhat.com>
>>> Thanks!
>>> I had a similar patch for mergeable too, though it's trickier there
>>> as host has a lot of flexibility in sizing buffers.
>>> Looks like a good intermediate step to me.
>> Yes, I think it's more tricky for the case of mergeable buffer:
>>
>> 1) we need reserve NET_SKB_PAD + NET_IP_ALIGN for each buffer, this will
>> break rx frag coalescing
>> 2) need tailroom for skb_shinfo, so it won't work for all size of packet
>>
>> Thanks
> Have you seen my prototype?

Not yet, please give me a pointer.

>   It works with qemu in practice,
> just needs to cover a bunch of corner cases.

Sounds good, if you wish I can help to finalize it.

Thanks

>
>>>
>>> Acked-by: Michael S. Tsirkin<mst@redhat.com>
>>>

Thread

[PATCH net-next] virtio-net: switch to use build_skb() for small buffer Jason Wang <jasowang@redhat.com> - 2017-02-21 09:50 +0100
  Re: [PATCH net-next] virtio-net: switch to use build_skb() for small  buffer "Michael S. Tsirkin" <mst@redhat.com> - 2017-02-21 15:40 +0100
    Re: [PATCH net-next] virtio-net: switch to use build_skb() for small  buffer Jason Wang <jasowang@redhat.com> - 2017-02-22 04:00 +0100
      Re: [PATCH net-next] virtio-net: switch to use build_skb() for small  buffer "Michael S. Tsirkin" <mst@redhat.com> - 2017-02-22 04:10 +0100
        Re: [PATCH net-next] virtio-net: switch to use build_skb() for small  buffer Jason Wang <jasowang@redhat.com> - 2017-02-22 04:20 +0100
          Re: [PATCH net-next] virtio-net: switch to use build_skb() for small  buffer Jason Wang <jasowang@redhat.com> - 2017-02-22 04:40 +0100
          Re: [PATCH net-next] virtio-net: switch to use build_skb() for small  buffer "Michael S. Tsirkin" <mst@redhat.com> - 2017-02-22 04:50 +0100
            Re: [PATCH net-next] virtio-net: switch to use build_skb() for small  buffer Jason Wang <jasowang@redhat.com> - 2017-02-22 11:40 +0100
  Re: [PATCH net-next] virtio-net: switch to use build_skb() for  small buffer David Miller <davem@davemloft.net> - 2017-02-21 18:30 +0100
  Re: [PATCH net-next] virtio-net: switch to use build_skb() for small  buffer John Fastabend <john.fastabend@gmail.com> - 2017-02-22 18:20 +0100
    Re: [PATCH net-next] virtio-net: switch to use build_skb() for small  buffer Jason Wang <jasowang@redhat.com> - 2017-02-23 03:50 +0100

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