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Re: [PATCH net-next] macvtap/macvlan: use IFF_NO_QUEUE

From Jason Wang <jasowang@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH net-next] macvtap/macvlan: use IFF_NO_QUEUE
Date 2015-08-25 13:40 +0200
Message-ID <q1kK7-5cL-29@gated-at.bofh.it> (permalink)
References <q0Vsl-2pv-1@gated-at.bofh.it> <q1juF-3vj-17@gated-at.bofh.it>
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On 08/25/2015 06:17 PM, Michael S. Tsirkin wrote:
> On Mon, Aug 24, 2015 at 04:33:12PM +0800, Jason Wang wrote:
>> > For macvlan, switch to use IFF_NO_QUEUE instead of tx_queue_len = 0.
>> > 
>> > For macvtap, after commit 6acf54f1cf0a6747bac9fea26f34cfc5a9029523
>> > ("macvtap: Add support of packet capture on macvtap
>> > device."). Multiqueue macvtap suffers from single qdisc lock
>> > contention. This is because macvtap claims a non zero tx_queue_len and
>> > it reuses this value as it socket receive queue size.Thanks to
>> > IFF_NO_QUEUE, we can remove the lock contention without breaking
>> > existing socket receive queue length logic.
>> > 
>> > Cc: Patrick McHardy <kaber@trash.net>
>> > Cc: Vladislav Yasevich <vyasevic@redhat.com>
>> > Cc: Michael S. Tsirkin <mst@redhat.com>
>> > Signed-off-by: Jason Wang <jasowang@redhat.com>
> Seems to make sense. Give me a day or two to get over the jet lag
> (and get out from under the pile of mail accumulated while I was traveling),
> I'll review properly and ack.
>

A note on this patch: only default qdisc were removed but we don't lose
the ability to attach a qdisc to macvtap (though it may cause lock
contention on multiqueue case).
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[PATCH net-next] macvtap/macvlan: use IFF_NO_QUEUE Jason Wang <jasowang@redhat.com> - 2015-08-24 10:40 +0200
  Re: [PATCH net-next] macvtap/macvlan: use IFF_NO_QUEUE "Michael S. Tsirkin" <mst@redhat.com> - 2015-08-25 12:20 +0200
    Re: [PATCH net-next] macvtap/macvlan: use IFF_NO_QUEUE Jason Wang <jasowang@redhat.com> - 2015-08-25 13:40 +0200
      Re: [PATCH net-next] macvtap/macvlan: use IFF_NO_QUEUE Vlad Yasevich <vyasevic@redhat.com> - 2015-08-25 18:40 +0200
        Re: [PATCH net-next] macvtap/macvlan: use IFF_NO_QUEUE Jason Wang <jasowang@redhat.com> - 2015-08-26 07:50 +0200
          Re: [PATCH net-next] macvtap/macvlan: use IFF_NO_QUEUE "Michael S. Tsirkin" <mst@redhat.com> - 2015-08-27 12:50 +0200
            Re: [PATCH net-next] macvtap/macvlan: use IFF_NO_QUEUE Jason Wang <jasowang@redhat.com> - 2015-08-28 04:50 +0200
              Re: [PATCH net-next] macvtap/macvlan: use IFF_NO_QUEUE Vlad Yasevich <vyasevic@redhat.com> - 2015-08-28 14:30 +0200
                Re: [PATCH net-next] macvtap/macvlan: use IFF_NO_QUEUE Jason Wang <jasowang@redhat.com> - 2015-08-31 04:50 +0200

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