From: "Michael S. Tsirkin" <m...@redhat.com>
Date: Wed, 13 Apr 2016 13:26:51 +0300
> On Wed, Apr 13, 2016 at 11:04:47AM +0200, Paolo Abeni wrote:
>> This patch disables the default qdisc by explicitly setting the
>> IFF_NO_QUEUE private flag so that now the tun xmit path do not
>> require any lock by default.
>>
>> The default qdisc was first removed as a side effect of commit
>> f84bb1eac027 ("net: fix IFF_NO_QUEUE for drivers using alloc_netdev")
>> and recently restored with commit 016adb7260f4 ("tuntap: restore default
>> qdisc")
>>
>> Signed-off-by: Paolo Abeni <pab...@redhat.com>
>
> I wonder about this back and forth.
> Jason, do you see a workload where the default qdisc
> is preferable?
I don't think you should change this, putting the default back was a
bug fix.
I think this series is taking way too many liberties in order to
achieve locklessness, in my opinion.
If you have proper multi-queue, the qdisc lock and the netdev transmit
lock are almost completely free.
