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Date: Mon, 25 Apr 2016 18:50:44 +0300
From: Konstantin Belousov <kostikbel@gmail.com>
To: Ruslan Bukin <br@FreeBSD.org>
Cc: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-head@freebsd.org
Subject: Re: svn commit: r298580 - in head/sys/riscv: include riscv
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On Mon, Apr 25, 2016 at 02:47:51PM +0000, Ruslan Bukin wrote:
> Author: br
> Date: Mon Apr 25 14:47:51 2016
> New Revision: 298580
> URL: https://svnweb.freebsd.org/changeset/base/298580
> 
> Log:
>   o Implement shared pagetables and switch from 4 to 3 levels page
>   memory system.

> +/* An entry in the list of all pmaps */
> +struct pmap_list_entry {
> +	SLIST_ENTRY(pmap_list_entry) pmap_link;
> +	struct pmap *pmap;
> +};

This is weird. Why do you need separate structure to track the all
pmaps list, instead of embedding the list link into pmap itself ? In
particular, the pmap_list_entry.pmap pointing to the pmap looks strange.

And why do you use single-linked list for the container where you need
to remove elements ?  The cost is the iteration over the whole container
on removal, vs. additional pointer in each pmap.