netdev - Re: [RFC] net: remove busylock

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1463683450.18194.220.camel@edumazet-glaptop3.roam.corp.google.com>
Date:	Thu, 19 May 2016 11:44:10 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org, aduyck@...antis.com
Subject: Re: [RFC] net: remove busylock

On Thu, 2016-05-19 at 11:12 -0700, David Miller wrote:
> 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.

Ticket spinlocks are actually gone, these are now MCS.

But yes, point taken ;)