netdev - Re: [RFC] net: remove busylock

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Message-Id: <20160519.111208.1949769629804288508.davem@davemloft.net>
Date:	Thu, 19 May 2016 11:12:08 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	netdev@...r.kernel.org, aduyck@...antis.com
Subject: Re: [RFC] net: remove busylock

From: Eric Dumazet <eric.dumazet@...il.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.