From: Eric Dumazet <eric.duma...@gmail.com>
Date: Thu, 19 May 2016 10:08:36 -0700
> busylock was added at the time we had expensive ticket spinlocks
>
> (commit 79640a4ca6955e3ebdb7038508fa7a0cd7fa5527 ("net: add additional
> lock to qdisc to increase throughput")
>
> Now kernel spinlocks are MCS, this busylock things is no longer
> relevant. It is slowing down things a bit.
...
> That would be a 8 % increase.
Presumably only for x86-64 and other platforms that actually are using
the ticket spinlocks.
For others it would be a regression.
