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Re: [PATCH net-next V2 3/3] tap: XDP support

From Jason Wang <jasowang@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH net-next V2 3/3] tap: XDP support
Date 2017-08-12 04:50 +0200
Message-ID <uduEV-3fB-3@gated-at.bofh.it> (permalink)
References <udgBY-315-9@gated-at.bofh.it> <udgBZ-315-43@gated-at.bofh.it> <udrnI-1gO-7@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On 2017年08月12日 07:12, Jakub Kicinski wrote:
> On Fri, 11 Aug 2017 19:41:18 +0800, Jason Wang wrote:
>> This patch tries to implement XDP for tun. The implementation was
>> split into two parts:
>>
>> - fast path: small and no gso packet. We try to do XDP at page level
>>    before build_skb(). For XDP_TX, since creating/destroying queues
>>    were completely under control of userspace, it was implemented
>>    through generic XDP helper after skb has been built. This could be
>>    optimized in the future.
>> - slow path: big or gso packet. We try to do it after skb was created
>>    through generic XDP helpers.
>>
>> Test were done through pktgen with small packets.
>>
>> xdp1 test shows ~41.1% improvement:
>>
>> Before: ~1.7Mpps
>> After:  ~2.3Mpps
>>
>> xdp_redirect to ixgbe shows ~60% improvement:
>>
>> Before: ~0.8Mpps
>> After:  ~1.38Mpps
>>
>> Suggested-by: Michael S. Tsirkin <mst@redhat.com>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
> Looks OK to me now :)
>
> Out of curiosity, you say the build_skb() is for "small packets", and it
> seems you are always reserving the 256B regardless of XDP being
> installed.  Does this have no performance impact on non-XDP case?

Have a test, only less than 1% were noticed which I think could be ignored.

Thanks

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Thread

[PATCH net-next V2 3/3] tap: XDP support Jason Wang <jasowang@redhat.com> - 2017-08-11 13:50 +0200
  Re: [PATCH net-next V2 3/3] tap: XDP support Jakub Kicinski <kubakici@wp.pl> - 2017-08-12 01:20 +0200
    Re: [PATCH net-next V2 3/3] tap: XDP support Jason Wang <jasowang@redhat.com> - 2017-08-12 04:50 +0200
      Re: [PATCH net-next V2 3/3] tap: XDP support "Michael S. Tsirkin" <mst@redhat.com> - 2017-08-14 18:10 +0200
        Re: [PATCH net-next V2 3/3] tap: XDP support Jason Wang <jasowang@redhat.com> - 2017-08-15 07:10 +0200
          Re: [PATCH net-next V2 3/3] tap: XDP support "Michael S. Tsirkin" <mst@redhat.com> - 2017-08-16 05:50 +0200
  Re: [PATCH net-next V2 3/3] tap: XDP support Daniel Borkmann <daniel@iogearbox.net> - 2017-08-14 10:50 +0200
    Re: [PATCH net-next V2 3/3] tap: XDP support Jason Wang <jasowang@redhat.com> - 2017-08-15 07:00 +0200

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