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Date: Wed, 10 Apr 2013 10:20:59 +0400
From: Gleb Smirnoff <glebius@FreeBSD.org>
To: Andre Oppermann <andre@FreeBSD.org>
Subject: Re: svn commit: r249318 - in head/sys: kern net netinet
Message-ID: <20130410062059.GZ76816@FreeBSD.org>
References: <201304092102.r39L2LrO047044@svn.freebsd.org>
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On Tue, Apr 09, 2013 at 09:02:21PM +0000, Andre Oppermann wrote:
A> Author: andre
A> Date: Tue Apr  9 21:02:20 2013
A> New Revision: 249318
A> URL: http://svnweb.freebsd.org/changeset/base/249318
A> 
A> Log:
A>   Change certain heavily used network related mutexes and rwlocks to
A>   reside on their own cache line to prevent false sharing with other
A>   nearby structures, especially for those in the .bss segment.
A>   
A>   NB: Those mutexes and rwlocks with variables next to them that get
A>   changed on every invocation do not benefit from their own cache line.
A>   Actually it may be net negative because two cache misses would be
A>   incurred in those cases.

Although change is theoretically correct, IMO, such change should be
supported by experimental performance benchmarking data.

-- 
Totus tuus, Glebius.