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Date: Sat, 4 Aug 2018 10:48:17 +0300
From: Konstantin Belousov <kostikbel@gmail.com>
To: Gleb Smirnoff <glebius@freebsd.org>
Cc: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-head@freebsd.org
Subject: Re: svn commit: r336047 - in head/sys: amd64/include i386/include sys
Message-ID: <20180804074817.GH6049@kib.kiev.ua>
References: <201807061950.w66Joibw081390@repo.freebsd.org>
 <20180803222739.GH420@FreeBSD.org>
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On Fri, Aug 03, 2018 at 03:27:39PM -0700, Gleb Smirnoff wrote:
>   Hi Konstantin,
> 
> On Fri, Jul 06, 2018 at 07:50:44PM +0000, Konstantin Belousov wrote:
> K> Author: kib
> K> Date: Fri Jul  6 19:50:44 2018
> K> New Revision: 336047
> K> URL: https://svnweb.freebsd.org/changeset/base/336047
> K> 
> K> Log:
> K>   Expand x86 struct pcpus to UMA_PCPU_ALLOC_SIZE AKA PAGE_SIZE.
> K>   
> K>   This restores counters(9) operation.
> K>   Revert r336024. Improve assert of pcpu size on x86.
> K>   
> K>   Reviewed by:	mmacy
> K>   Sponsored by:	The FreeBSD Foundation
> K>   Differential revision:	https://reviews.freebsd.org/D16163
> 
> Since this has been broken already several times as people who edit
> surrounding code don't understand the magic, and since now we round
> the struct pcpu size to PAGE_SIZE anyways, what about stop carefully
> craft the padding and just change alignment of struct pcpu to PAGE_SIZE?
I do not see how it would avoided that breakage.  Also, I like the
explicitness in the padding, it is useful when new pcpu members are
added.  I have to do that more than once this year.