Re: [PATCH net] macvtap: unbreak receiving of gro skb with frag list

From	Jason Wang <jasowang@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH net] macvtap: unbreak receiving of gro skb with frag list
Date	2015-10-27 04:00 +0100
Message-ID	<qo2Eq-7Yj-5@gated-at.bofh.it> (permalink)
References	(1 earlier) <qmKJB-2QB-39@gated-at.bofh.it> <qnGue-31H-7@gated-at.bofh.it> <qnJ8J-4Gh-3@gated-at.bofh.it> <qnJV7-4WM-1@gated-at.bofh.it> <qnLtU-5Xl-19@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 10/26/2015 04:30 PM, Michael S. Tsirkin wrote:
> On Mon, Oct 26, 2015 at 02:53:38PM +0800, Jason Wang wrote:
>>
>> On 10/26/2015 02:09 PM, Michael S. Tsirkin wrote:
>>> On Mon, Oct 26, 2015 at 11:15:57AM +0800, Jason Wang wrote:
>>>> On 10/23/2015 09:37 PM, Michael S. Tsirkin wrote:
>>>>> On Fri, Oct 23, 2015 at 12:57:05AM -0400, Jason Wang wrote:
>>>>>> We don't have fraglist support in TAP_FEATURES. This will lead
>>>>>> software segmentation of gro skb with frag list. Fixes by having
>>>>>> frag list support in TAP_FEATURES.
>>>>>>
>>>>>> With this patch single session of netperf receiving were restored from
>>>>>> about 5Gb/s to about 12Gb/s on mlx4.
>>>>>>
>>>>>> Fixes a567dd6252 ("macvtap: simplify usage of tap_features")
>>>>>> Cc: Vlad Yasevich <vyasevic@redhat.com>
>>>>>> Cc: Michael S. Tsirkin <mst@redhat.com>
>>>>>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>>>>> Thanks!
>>>>> Does this mean we should look at re-adding NETIF_F_FRAGLIST
>>>>> to virtio-net as well?
>>>> Not sure I get the point, but probably not. This is for receiving and
>>>> skb_copy_datagram_iter() can deal with frag list.
>>> Point is:
>>> - bridge within guest
>>> - assigned device creating gro skbs with frag list bridged to virtio
>> I see, but this problem looks not specific to virtio. Most cards does
>> not support frag list.
> These will be slower when used with a bridge then, won't they?

For forwarding, not sure. GRO has latency and cpu overhead anyway.

Anyway I can try to add the support for this.
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Thread

[PATCH net] macvtap: unbreak receiving of gro skb with frag list Jason Wang <jasowang@redhat.com> - 2015-10-23 07:00 +0200
  Re: [PATCH net] macvtap: unbreak receiving of gro skb with frag  list David Miller <davem@davemloft.net> - 2015-10-23 11:20 +0200
  Re: [PATCH net] macvtap: unbreak receiving of gro skb with frag list "Michael S. Tsirkin" <mst@redhat.com> - 2015-10-23 15:40 +0200
    Re: [PATCH net] macvtap: unbreak receiving of gro skb with frag list Jason Wang <jasowang@redhat.com> - 2015-10-26 04:20 +0100
      Re: [PATCH net] macvtap: unbreak receiving of gro skb with frag list "Michael S. Tsirkin" <mst@redhat.com> - 2015-10-26 07:10 +0100
        Re: [PATCH net] macvtap: unbreak receiving of gro skb with frag list Jason Wang <jasowang@redhat.com> - 2015-10-26 08:00 +0100
          Re: [PATCH net] macvtap: unbreak receiving of gro skb with frag list "Michael S. Tsirkin" <mst@redhat.com> - 2015-10-26 09:40 +0100
            Re: [PATCH net] macvtap: unbreak receiving of gro skb with frag list Jason Wang <jasowang@redhat.com> - 2015-10-27 04:00 +0100
              Re: [PATCH net] macvtap: unbreak receiving of gro skb with frag list "Michael S. Tsirkin" <mst@redhat.com> - 2015-10-27 10:10 +0100
                Re: [PATCH net] macvtap: unbreak receiving of gro skb with frag list Jason Wang <jasowang@redhat.com> - 2015-10-28 04:00 +0100

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